Well I'm still slogging away at it, though it's not made any easier having a serious bug to contend with. For some reason there will be a race, or more, that won't appear in any of the screeens after meeting them. So I can't contact them, place spies with them, or get any sort of info. They don't even show up in the United Planets meetings. It doesn't happen all the time but when it does it pretty much screws up the game and I have to restart a new one.
Anyhow I'm learning to live with colonizing pace. About the only ones I have problems with now with are the Krynn and the Thalan, I'm pretty much out-colonizing everyone else. The Thalans I can sort of understand as they get the bonuses for Factory production, but I see no reason for the Krynn always having so many colonies. I hadn't actually considered them leasing their ships, that could explain alot frankly. I've also noticed that the build Factories only approach isn't as dire as I first thought. By going for as many colonies as possible at first my economy at one point slows down so that most planets aren't building anything anyway. So by the time things start picking up again they may only have 1 or 2 Factories actually built, leaving the rest of the tiles still available for more diversity. The only real exception is the capital, but once the other colonies start producing Colony ships of their own I can diversify that a bit more as well.
As for the Krynn and the Thalan, I've just finished adding 12 more races to the game thanks to Fomis' great artwork so they won't always be appearing in my game to pisss me off.