We have only seen performance of AMD’s R9 Fury X in Far Cry 4 and not compared against anything. If you were wondering about performance check out the graph below that shows 4K performance of the card vs the GeForce GTX 980 Ti across 12 games!
Now of course these numbers are supplied by AMD and they are not going to release this information unless it paints a good picture of the card. But overall things look to be pretty good for the Fury X. Although wait for full in-depth reviews, which will be released on the 24th.