I've had this setup since early July. The card is an AMD Radeon HD 6450 and I'm using the version of Catalyst which was provided in Jockey.
When Compiz is enabled, I get problems with laggy window movement (even with the known compiz opengl changes) and laggy scrolling. To remedy this, I simply use Classic mode with no effects. The problem here is that any video/3d/etc (except Flash stuff) will be extremely glitchy.
The window flickers and always remains in the foreground.
This happens with games, movies, or just about anything regarding video playback. I'm assuming these issues are somewhat due to the fact that my GPU is fairly new.
Any help would be great :)