Every crimson version I've tried has been worse than catalyst 15.11.1 so I've been sticking with that. Fury X overclock is at 1125 525, 4790k @ 4.6Ghz, 32Gb DDR3 2400 CL10. Tried various optimisation mods as well as unmodded and still get rubbish performance. I force 32x tessellation because the god rays flicker like crazy otherwise. I use clock blocker to prevent throttling, temps are low as using full water cooling loop. Just figured the game was unoptimised as hell... was excited about trying 16.1.1 as has a crossfire profile but apparently it's useless with v1.3.
What FPS are you getting then? Test walking around sanctuary or in the streets around corvega