I was the first one in my guild to get 4 set (we ran 2x30 man HC). I wouldnt say the 2 piece is shit, its actually pretty good and even better at multiple targets.
Just look at this from iron maidens:
2 set energy gain:
https://www.warcraftlogs.com/reports...l=103&source=6
4 set dmg portion:
https://www.warcraftlogs.com/reports...-done&source=6
the 2 set bonus actually gave me more energy than tigers fury and the 4 set is about 5% ish of my dmg depending on the fight. The energy regen would ofc be lower with less targets to put bleeds on, but still pretty good imo.