Maybe...but upgraded 2/2.
That 4pc is nice, but for me, sometimes I find it hard to use it simultaneosly with the imps. But im not the pro
I'm in the same boat. While it's nice to have higher DS uptime, previously I had it macro'd to Blood Fury. I can only use it together with BF on the pull now. I wish they would have increased the percentage maybe. Like DS now provides 35% haste/mastery/crit.
I think the pure stat upgrade from having heroic feng chest over LFR chest is enough to say no. I'd say stick with 2 piece and try to get another heroic piece to replace your other tier piece (Assuming you're using 3 tier pieces at the moment of course).