Hi there. I maintain OPM. One note, OPM fixes mod compatibility bugs but it does NOT fix mod compatibility balance (that's what FF is for). Currently the go-to mod compatibility exploit is to use CBM's cheap GoR and Possession on certain freespawn from AE's pretenders, notably Mother of Tuatha's Tuatha freespawn. I highly, highly recommend you
ban this in a house rule.
edit: Oh, and on the mods. There are actually a LOT of stuff in them that should feel familiar to anyone who plays CBM.
AG was originally based on CBM pretenders, but makes pretty much everything MORE powerful. It makes god pick just as central to strategy as nation pick, in my opinion.
Still, there are some pretenders that are purely CBM.
AE is originally based on EDM, so there are all the classic EDM summons. Some of them are juiced up slightly (and the Zmey is nerfed into the ground. kind of a metagame nerf, but we overused it horribly on Something Awful). The key difference in AE however, are the abundance of good-path mage summons. The Wraith Lord, Tarrasque, and Kraken are diversity machines. All the Royalty have super high paths. This means wide path access is much easier in the lategame compared to EDM/CBM.
edit2: The OPM site is actually here
https://sites.google.com/site/dominionsenhancedmod/home but it doesn't matter because the
proactiveapathy mirror is basically always up-to-date and you can find the mods individually there and the individual mods have patch notes in the .dm