The key part of this plan of course was my delusion that I had more workable land than Lord Parkin did, and I spent the next phase of the game settling and developing it. I certainly could have done this more efficiently than I did it, but I think I did a respectable job. If I did it again I'd build more workers sooner. I would also decide a lot sooner on locations for the national wonders, some of which I delayed much longer than they ought to have been. Not much more to say about that part though.
Although tech trading was off, Lord Parkin made the observation that espionage could be used to partly work around this, by way of tech stealing. Combine this with the ability to run 100% espionage slider in one civ while still running research in the other and you have what seemed like a fairly decent plan. So, I made it my mission to optimise this as much as possible.
Of course, there was one big killer to the whole idea of tech-stealing as a workaround to no-tech-trading that was specific to this crazy 2-civ-teams setup. Technologies in team games already have an increase to their base cost - an extra +50% in this case of two civs. However, on top of this, espionage missions also cost exactly twice as much - supposedly for the same reasons. What this means though is that tech stealing is hit with a double-whammy of cost penalties, and the EP<->beaker comparison is flat out twice as bad for EPs as it would be in a normal game. To me, this was a wrong decision in the game design. The increase in tech costs is fine, it makes senes. The passive EP mission costs might well need to be doubled as well. However, the vast majority of active missions, in my opinion, should not be doubled. Sure, you can generate EPs twice as fast, but you also need twice as many to actually get the same benefit. But anyway, that's the way the game works, and the offshoot of it was that tech stealing was only half as effective. Were I able to steal twice the number of techs that I stole I might even have caught up, but nevermind.
On the whole, tech stealing wasn't a replacement for tech trading. It would instead best be compared to direct research, and although it did come out ahead in the end, it was only through all the effort detailed below. Here's a summary of the comparison.
First Round Bonuses:
(EPs) <->
(Beakers)
? <->
Monastaries, Free Religion. A win for beakers, but monasteries obsolete and free religion is in place of better religious civics (although ok the same could be said for Nationhood below).
Nationhood <->
Libraries. Writing comes a lot earlier than Nationalism of course, but by the time it was all set up I nearly had both techs anyway, and I still hadn't built the libraries. In general though research gains an early advantage here.
Scotland Yard <->
Academy + Oxford. On its own Scotland Yard is twice the multiplier bonus of an academy, but the lack of an equivalent to Oxford (by which I mean a buildable national wonder) roughly balances these out.
Jail <->
Observatory + University. The jail wins out here by being cheaper, particularly than the other two combined, and providing side benefits (4 free EPs and war weariness reduction).
Intelligence Agency <->
Laboratory. Not even really a sensible comparison, the Agency wins out for sure, coming so much earlier.
On the whole, science wins out early on with libraries and monastaries, and continues along strong with Academies easier to come by than Scotland Yard (two library specialists, compared to one spy from the later arriving courthoues), and the Academy+Oxford+Beaurocracy capital the clear winner in a small empire. Later on however EPs pull ahead, with slightly more multiplier buildings available (and cheaper on the whole) for a large sprawling empire, multiple Scotland Yards outperforming multiple Academies, the side benefit of the EP buildings everywhere making the most of the free building generated EPs and more productive specialists (4 eps plus a free beaker from a spy compared to 3 beakers from a scientist).
In any case though the differences are basically fairly small, at least to the extent that the details of a particular game situation can reverse the general rule and other factors may well come into play.
Second Round Bonuses
I'll separate the two sets here.
Beakers
+20% pre-requisite bonus. This is a 20% bonus for each "optional" pre-requisite - the ones with the arrows on the tree, rather than the little icon in the top right. Of note is the fact that if a tech only has one "optional" pre-requisite (making it not all that optional really) you still get a 20% bonus, so most of the time this 20% bonus is active. For some techs it's a 40% bonus, for Flight it's missing. Did they give Flight two compulsary techs rather than one of each to make it deceptively slow to research and relatively cheaper to steal? Or did they just do it to help the layout of the tech tree? You be the judge. Generally then you can say there's a 20% bonus here, but be aware that if you're doing both beaker and EP research then you should prefer to steal Flight and self-research anything you've claimed two or more optionals for.
+5% bonus for each civ who has the tech. If you're comparing to tech stealing then you generally should assume at least one other civ has the tech.
On the whole, these combine additively to a net 1.25x mutliplier, or equivalently 0.8 reduction in cost.
EPs
Unlike most bonuses in this game, these are all applied multiplicitively.
1.25x Tech Steal Mission Cost. This is a fixed penalty modifier applied to the tech steal mission, to give the base mission cost. Presumably to somewhat modify the overall balance of stealing techs.
0.8x Trade route modifier. This doesn't just require trade routes connected like I originally thought, but you have to have an actual trade route with that city, in the sense of the city being listed in one of your cities lists of trade routes. I'm not sure whether you need your own city to list the target city, or you need one of your cities listed in the target city, and I'm not sure in any case how to influence either of those in your favour (other than indirectly by closing borders or getting your target to close borders with other civs). I do know I went most of the game without this bonus, despite the two teams having almost no trade routes except with each other (with a small exception of Rome/Netherlands). So you can't rely on it.
0.6x Shrine modifier. You need to have a state relgion, you need to own the founding city with the shrine built, the state religion needs to not be the target's state religion, but needs to be present in the city. If you don't have the founding city or shrine though you can still get 0.85x here at least.
0.5x to 1.0x Culture modifier. To get it down to 0.5 you need to have all the culture in the city (good for cities you've recently lost). At break-even culture it's at 0.75x. I tried to set this one up, but Lord Parkin stacked on the culture buildings despite my asking him not to, to the point where the culture from the espionage target city was making a massive nuisance of itself and eating away at the surrounding cities. So I had this bonus at first, but slowly lost it.
1.0+ Distance penalty. A penalty for the distance of the city from the capital.
0.5x to 2.0x Espionage accumulation modifier. This is based on the total number of EPs you have accumulated during the game, spent or unspent, and regardless of who they're against - I wouldn't be surprised if it even counts the ones lost before you make any contact. If you're planning on using the espionage slider and your opponent isn't, then this should end up pretty close to an extra 0.5x in your favour, otherwise it'll probably be close to 1.0x.
0.5x Stationary unit modifier. You get this bonus by simply leaving the spy still for 5 turns. you should always make sure you get this for stealing tech, crazy not to. Of course the upshot of this is you need to plan more than 5 turns ahead. And bring a lot of spies, as they will get caught while sitting there and also fail the mission occasionally.
2.0x Team game modifier. In general Nx where N is the number of civs in your team. The real kick in the pants to using EPs in a 2 civs per team game.
2.0x Counter-espionage modifer. If they do not want you to steal their tech then this is an easy way for them to make it not worth the bother.
So, putting it all together, you can in theory do as well as 0.075x in single-civ games, 13 techs for the price of 1! However, it's never quite that good, and takes some setting up. For stealing from your enemies, the best target is a city that was yours but has recently been conquered. Of course there's down sides to being in that situation as well
On the whole you're unlikely to end up ahead if they run the counter-espionage mission.
For co-operative tech stealing, the ideal situation is to set up a city very near the capital, under serious culture pressure for instance from the capital), with a trade route, a religion you've founded and the target isn't running. It works even better if it's one sided tech stealing too. So this is exactly what I did. I settled a city near the capital, naming it the "Acni Embassey", and gifted it to Lord Parkin. The city was designed to be under culture pressure from the capital, and giving a very small (1.03x as it turned out) distance penalty. I burned a scientist to pop Philosophy while the religion was still available, switched to that religion and spread it to the embassey city.
On the whole I got no-where near 0.075x of course, but could generally get it down to about 0.5x. With culture close to 50% the culture modifier is only 0.75x, which is as good as it can realistically get without the city revolting all the time. The espionage accumulation modifier doesn't really kick in until you've been doing it a while and have a good lead on them, at which point it gets down to about 0.6x at best. I mostly didn't have the trade route modifier. So on the whole, it was 1.25(base) x 0.6(shrine) x ~0.65(between culture and espionage) x 1.03(distance) x 0.5(stationary) x 2.0(team penalty) ~= 0.5
Compared to the 0.8 for research, it was about a 60% speed up in research rate. Huge really, but not game breaking, and as it turned out not enough for me to ever catch up.
This was of course always meant to be mutual tech stealing, not just me sponging, but because I never caught up it only ever went one way. This seems a little generous from Lord Parkin's perspective, but the reality was it worked quite well for him. There was the metagame issue of demonstrating himself a good ally to have. It kept me dependent on him, secured him a long term ally to pretty much lock in his lead, and at the end of the day the fact that I never caught up to him has to be good news for him anyway, right?