Whew, just got done reading this thread over the past few hours. Lots of great things going on. Here are my two pennies on some issues:
-As JeBuS27 got at, adjusting anything economically (as some have brought up maintenance costs/expansions speeds) will throw a LOT of things out of whack. First, it can really unbalance civics, so getting to a certain civic may be the only viable path to victory. Secondly, since gold and research are the same base commodity, adjusting the former impacts the latter. Lastly, enabling expansion at a faster-than-relative rate means that you're increasing research rates as more of a power function than linearly. That is, modding percentages linearly (as is all we've looked at) is no longer adequate if you enable expansion to occur in a non-linearly balanced manner. Basically, from the moment you allow expansion to occur 1% faster, you have to pinpoint the exact percentage that that increases research due to the added commerce, and that elusively-quantified impact IS DYNAMIC for each turn that occurs after the deviation from the linearly balanced model of the original settings. So expanding three turns earlier than linearly balanced may result in huge tech discovery differences by the modern age. All of the above applies also to allowing production of wealth, research, or culture at earlier junctures of the game. So I would oppose doing much if any wealth tweaking in this mod, especially in the early game.
-Civics. This is going to require the most playtesting. The idea is that, as the mods are shaping up right now, civics that adjust military unit experience will be unbalanced, as those military promotions were meant to be enough to give a civ a legit advantage when they had, say, 15 units in a given era. But now they will put out perhaps 150. What will end up happening is that units which begin with higher experience as a result of a trait or civic will be more likely to fight more battles under these settings, and therefore be more likely to create a disparity in game balance compared to a civic that gives a civ a non-military advantage, especially when the effects of promotions are added in (that is, units that start with a promotion or two are more likely to win, therefore more likely to get promoted more, therefore more likely to win at even a HIGHER rate...). The counter-argument is that "well, 150 upgraded units against 150 non-upgraded units isn't more of an advantage than 15 upgraded units over 15 non-upgraded units, right?" Well, we don't know that. Civics were balanced based on the default civ speed, so perhaps some of the military experience civs had to be given disproportionate advantages to compensate for the small windows of opportunities for combat. Basically, if the benefit of a military civic for any one unit is equal to (benefit per battle) * (battles), then adjusting the second half of that formula can throw the whole thing out of whack, and we can't be guaranteed that the non-military civics scale proportionately. So, to maintain the balance of different types of strategies and victories, civics/buildings that give military advantages will have to be monitored and possibly adjusted later.
-Anarcy. Under these mods, anarchy becomes not much of an issue, since one turn becomes less valuable. Anarchy needs to be scaled along with everything else. Then, the spiritual trait has to be balanced if it creates a problem. Keeping anarchy at just one turn but increasing the total number of turns reduces the value of the spiritual trait. Perhaps anarchy could be scaled as a function of total turns.
-Pillaging improvements. Doubling worker time doesn't account for what will inevitably be increased pillaging due to more military units with many higher total movement points per era. Perhaps worker improvement time shouldn't quite be doubled but instead a little quicker than double. This probably won't be prevalent against the AI, but will have to be monitored in MP. Simply doubling worker times while vastly more than doubling the total number of military unit turns available per game may result in very undeveloped city terrain due to pillaging.
-Food/hammer/commerce balance. The very heart of the game balance system will get screwed up if GPP's aren't treated with care. They need to be properly scaled along with everything else, otherwise high food/high specialist cities become less valuable, and the entire civ terrain engine that balances around that becomes no longer balanced. Hilly and forested areas would become necessary for victory, and flatlands and coastal squares would be far less valuable. You may not like GP's much, but that's fodder for a different mod. Adjusting them in this mod opens up a can of worms that is far outside the scope of research and turn balance.
I think it is important that people realize the shortcomings of the game WRT this mod and accept them instead of trying to fix them to only create more and numerous and perhaps fatal errors and imbalances. Those "shortcomings" are:
-possibility that your cities will spend large periods of time producing military units or producing nothing at all
-possibility that expansion will be very slow
-possibility that most of your turns will simply be pressing the enter button
Those are all natural extensions of the mod. Trying to mod them out of it is trying to have your cake and eat it too, and could create more problems.