Regarding issues with BAT, there are definatly a few bugs and errors that get thrown by the default ethnic unit art from Varietas Delectica (just check your error logs to see), and I've found one definite critical error that can (rarely) cause a crash due to some bad reference in the Native American City art. But for the most part it is stable, and shouldn't be causing any critical bugs (I don't know about Vista though, it is quite a bit more touchy then XP). To fix this for the mod I've been working on, achilleszero has been working for the past month or so on cleaning up the ethnic unit and city art for Legends of Revolution.
Whoever is in charge of BAT might be interested in this. There are some mod specific art things done, but the vast majority of the model and graphics fixes are for Varietas Delectica in general. Bascially he's cut down the poly counts of everything to reasonable sizes (some where as high as 10,000, all units are now under 2000, and all city art is equivalent to default BtS), and fixed bad node and other references that kept showing up in the error logs. If you are interested in this, I can upload all the art seperately and remove the extra leaderheads and any mod specific units and buildings for BAT. Of course achilleszero would need to be credited for his work here.