I really can't agree with the above benchmark and overall results just because I tried BF4 with the latest Mantle patch and I noticed good performance but not that good as DirectX version (a bit lower framerate) and also strange hickups, it's not that smooth framerate, it's stuttering or something now and then (ex: the first level when you meet your comrades....hickups!)..
I have a Radeon R9 290 from Gigabyte and it's not OC at all.
Besides, I have problems with the new beta 14.1 driver, major ones but I will speak about this issues on another thread, the one related to 14.1 driver.
I had no problems at all with the 13.12 WHQL driver.
I'm in love with Amd since K5/K6 and earlier Radeon 9550 and now love R9 series and the fact Amd won the console wars!