Well, the discussions I remember were differently, but maybe different people had different opinions. Don't think we have to go into too much depth about that, as it's an empty discussion that will lead to no important points anyway.
You were talking about relocating existing population. If you didn't have tiles with decent food yields before getting the specialist slots, then how exactly did that city gain the additional population that now out of nowhere needs to be relocated?
No, you're just wrong here, and it doesn't get right just because you repeat it. Each pop consumes 2 food. Here's the proof:
And it doesn't matter if it's in a specialist slot or if it's working a tile.
Already covered most of that above and why it is not a good thing to just focus on getting maximum food in the last post - the thing about academies. This is not Civ 5 where stacking population is the most important thing.
Well, if there's no tile left that can build a tile improvement, then getting additional population in that city is very, very low priority anyway. It's still not worth wasting 255 production so you can, somewhere down the line, get +1 science from that additional pop that the mass digester may have squeezed out. I mean going to pop 10 requires 168 food - so that mass digester would need 79 turn to accumulate that 10th population if the alternative is a snow tile. If any ocean tile is available toe "bonus-pop" the mass digester gains you needs 168 turns. It's just not worth it.
(Already went through all of that above - see screenshot, you're wrong.)
Alright, so you ARE talking semantics.
No, Grower Specialists are EXACTLY as lacking as that building that I dreamed up there. You're trading 255 production for +1 science maybe somewhere down the line, if the game takes really, really long, then +2 science.
No. No, just no. Man, you're thinking a lot about that, but you're still missing the key problem that makes Grower Specialists useless at their core. The few situations where Growers COULD indeed be useful just don't happen. I mean taken to the extreme your argument comes down to: "If a city that has nothing but ice tiles need to sustain 8 population, then grower slots are really good." ...YEAH. That's right. But you'll never HAVE a city that has 8 population and nothing but ice tiles. It just can't happen - just as the examples that you mentioned can't happen.
And no, I'm not trying to ridicule your argument, I'm just trying to show you that it's the same thing. You cannot assume a situation where the city already >has< additional Population and then somehow loses the tiles they were working without explaining how the hell that happened. I mentioned the only situation I can think of in the last post (moving tiles between cities), but again: In this case working an academy is the efficient solution. No tiles free for academies? Well, then there's no reason to use growers, because the additional pop will also have no tiles to work and the investment would not pay out.
And that's really the problem about the examples you have given. Either the situation you presume doesn't make sense. Or the payout you get from using Growers is so little that it's better to set up an Academy (or whatever advanced tile improvement you prefer). And if you can't even set up an Academy because there are no free tiles then that pop is still better used to give +1 production while you use the 255 production you'd need to build the mass digester for other stuff - if you don't need anything else, then that's still 64 raw science that you get much faster than the additional pop could give you.
But yeah, other Specialists have more things going for them, I'm not even arguing against that.
If in the example above it were Scientists instead of Growers, yes, then the deal would look a lot different. The problem however is still that the Institute is basically the only Multi-Scientist Building along the way, so in efficient victories you'd need to give up the free endgame tech from the building quest, which means that getting the building early on is basically out of the question. The Xenonursery is great though - if you meet the requirements and have a low-food city with Xenomass (which... won't happen often, but every now and then).
Artists are once again mostly useless in "Mainstream"-Strategies (because you already get all the Culture-Production you need early on and additional Virtues have extremely steep uphill-costs). They may have more use in strategies that get less Culture than they need for all the virtues they want (although it's questionable if the virtues will be worth the loss in Tile Yields and there would probably be a better solution to solve that issue).
Engineers - good for quickly maxing Production for a while if needed for whatever reason. And you even get 2(4) for free on good buildings that are on good techs, that's the best thing about them. (edit: And of course in the "No tiles available"-Situation Engineer slots are the most available, good option to put additional pop in)
Traders are just the most horribly scaled Specialists and should never, never, never, never be used. But they have some utility if everything goes to and you need some additional turns to fix it. They're damage reduction, and again you get 2 for free on a building that you want anyway, so the opportunity/investment costs for making the slots available is 0.
Growers however? Nope.
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/edit:
Ah, right. I'm sorry.
I think most of your points are very reasonable and I agree with them. Especially the point that building quests should be visible somewhere (which is something that I was against in the past, but I changed my mind) - some building quests are just very important and to really evaluate a building that information needs to be readily available.
Manual Specialist Control is also something that would be really useful, just as a "Stagnate City Growth"-option. Although the latter one probably has not as much use as it had in Civ 5 it would still come in very handy.
Sponsor Abilities: I personally think they should be more powerful than what you mentioned, so Sponsors actually feel a lot different from each other - but of course, that would make balancing Effords a lot harder (and it would make my mod obsolete, so keep them grounded!). Your solution for Africa would not really work though, as the huge bonus have it that they don't have to build the relic early and get that culture rolling while being able to build something else. Later Relics just aren't as much of a deal. It's an awkward solution to this, but I think just making the Old Earth Relic cheaper (something like 30 Production, no Maintenance by default) to reduce the bonus passively would reduce both, the strength of Africa AND the Artists-Loadout at the same time.
