I've never used P96 since I don't have any cards that are supported by it. I prefer the feature set in CGX4 anyway.
Betatesting in #AmigaZeux we find that P96 users often have weird graphical bugs that we can't track down in code. P96 may be buggy, or its emulating of CGX may be buggy. And then again it could just be because our stuff is written for CGX in mind.