I tried them last night. It is very focused on Mantle, Double GPU, Battlefield 4... So I was naturally very excited, it´s my turf (and of many others as well ) Turns out it still does not deliver the same performance I´m getting from Catalyst 13.12 (DirectX 11) I´m running 7970 Xfire on i74770k, 16 GB RAM, SSD
Last night I did a quick test in the same server, same map (yes I swapped drivers a few times in few minutes interval - they call it next gen ) and I´m still getting more FPS (it was on Dawn Breaker) running Cat13.12 (70-100 FPS on all High setting; 5760*1080). Quick swap to Cat14.2 beta only to show 58-70 FPS (50/64 players or so...).
So, back to Cat13.12...
Mantle is still an absolute NO GO for R9280x Crossfire (an embarassing 30 FPS or even less).
Strange to see DirectX performing worst (not a bit worst but considerably worst), I was expecting same or better considering double GPU optimizations (for Mantle and Framepacing). I hope it´s a "beta issue"!