After experimenting with this tactic a bit under several different starting positions, my revised thoughts:
- I represented incorrectly the use of this tactic in the OP. In situations in which you have a lot of room to grow and good city locations, you are better off simply expanding normally to the standard (or at least my standard) 4-5 base cities and going for Education and the wonders there first. That is, the very standard strategy seems to put you in the best position if you have the luck of little early geographic pressure. I've tested, on a map with plenty of free space, where my empire was sitting after 120 turns of normal expansion and with an IIB strategy, and I believe normal expansion to be the preferable route in that scenario.
- the usefulness of this strategy is actually exactly the opposite of my claims in the OP. This strategy works great in starting situations much like the one Mazer described in his game with the Ottomans - that is, where you are boxed in by rival civs or generally have poor real estate for additional cities. The IIB strategy is essentially a deferred expansion through military conquest strat, and seems to work best when normal expansion is impossible or undesirable (due to crappy land). Indeed, in geographically challenged scenarios, it may well be the dominant strat for the civs which can really benefit from it (the ones with appropriate UUs).
- the Hanging Gardens is the first key to this strategy, and it is only through acquisition of this wonder that your empire is able to stay scientifically level with or slightly ahead of the AIs. Basically, population in the capital counts for a whole lot more scientifically than population in smaller cities because of the Library/Nat College effect.
The science value of 1 pop in a small city without a library: 1
The science value of 1 pop in a capital with a library and NC: 2.25
It is because of this that the Hanging Gardens allows you to keep up scientifically, and getting that wonder is absolutely crucial to this strat. Without normal expansion, if you don't get a monster capital, you're toast.
- with that in mind, the tech progression should clearly be:
Pottery
Writing
Mining
Philosophy (free from GL, in theory)
Archery
Animal Husbandry
The Wheel
Mathematics
...with probably Bronze/Ironworking next (*it may be worth it to throw in Masonry if you've got marble and/or a lot of stone*)
Construction should begin on the HG as soon as Mathematics is researched. I find that with the above tech progression I get the HG about 90% of the time if my production is good. Mathematics is a 3rd level tech and there are more possibilities for where the AI can go at that point, and therefore somewhat less competition than for the first round of wonders. Anyway, if you miss the HG, you need to change tactics immediately.
- the second key to this strat is having a strong melee/ranged unit that can be spammed once the Ironworks goes up, because you're going to have a window in which your military productive capacity is going to be really large relative to the AI, and you need to use that window to roll up a couple of neighbors and expand. Civs that rely heavily on mounted units will probably find that this strat interferes too much with their chivalry beelines, and civs that have no timely units to take advantage of the Ironworks will be somewhat disappointed with the results.
- this strat may be something approaching optimal under the conditions described above (decent production, geographically cramped, civ with appropriate units), but it seems to be a situational strat useful for a few civs to "make a breakout" of a tight starting spot, rather than an overall über strat that everyone should implement post haste.
- in multiplayer, if the starting position/civ played are appropriate, foregoing the struggle for the GL and teching directly to mathematics (so AH, Mining, Archery, TW, Mathematics) and immediately constructing the HG is probably the way to make this strat work. Unless someone else is beelining the HG (which I don't think anyone really does at this point), it will probably work, at which point one can either go straight to warmongering --> Ironworking, etc. or go back to Pottery-Writing-Philosophy.