Brian-
The main problem I'm having is with shoes! My guess is that any Poser conforming shoes that were modeled around a posed foot (instead of the default V4 base) don't "line up" in Carrara.
The other issue is that certain hair props won't accept their MAT poses in Carrara. This is a known issue that's not really widespread.
Shawn-
I think I'm just about done with Poser anyway. Maybe somebody's trying to tell me something :)