Hybrid crossfire has really iffy performance, and often times you're better off just using the APU by itself. Driver support for this kind of crossfire is really terrible and it suffers from microstuttering a lot. I'd suggest trying each card alone and seeing which one performs better.

Also, don't use the latest beta drivers (13.10). They're hit and miss with crossfire setups, but in my experience have been horrible. I dropped down by almost 50 fps with these. 13.4 seems to be the best performance at the moment.