I am going to request to change the name of this thread, and restart a new one for Latest Version announcments. There is a General Question thread. PLEASE use that for questions such as these.
LZ - No, the BAT Mod does not contain BUG, but you can rename the CustomAssets folder to Assets, and copy that over your Assets folder in BAT. If you put the new "BUG Mod" in the Root BTS folder, this will allow you use your settings between BAT and BUG. Just make sure to delete the old support files. This is everything in the directory BAT Mod besides the Assets folder, Help file, and BAT Mod.ini. Also rename The BAT Mod Help.chm to BAT Mod Help.chm to make sure the help file will work from the Options screen. I'm debating on how to release BAT right now, but will have a plan of action fairly soon.
GooglyBoogly - That's not something related to BUG, that's just how Civ works. If you change even one letter inside of any fille in Assets or CustomAssets, it will prevent a save working. I wish I had another solution for you, but any games that were locked, will have to be played out with 2.20. Unlocked games will work fine.