I spoke with Safu/Misams and according to him:
1) Combat Potency procs way less often as it should
2) Killing Spree cancels autoattacks while active.
Taralej you made the FoK + Killing Spree bug report so you know Combat Rogues should be dumping energy with FoK while KS is active but now I barely ever get near capping energy except during AR.
Take these two issues as little food for thought while trying to figure out what's wrong with our favorite spec.