@shadowstrike: yup if you make a major change to amai you find replays no longer fail to work. If you make very minor changes the replays still work. Basically changes to languages and strategies are what will stop compatability as they modify the blizzard.j file used for AMAI
Your correct about automatic upgrades. There is an inbuilt system so that upgrades are more likely to be researched the more units of a certain type there are. Of course you can still write in the upgrades yourself if you want to have the upgrade researched definatly at a certain point in time.
I'll look into increasing efficiency of the ancient expansion attacks.