I think the Greater Demons are still good. An awesome thirster is probably even better this edition. 7 S10 attacks with re-rolls is pretty damn good, plus S10 thunderstomp. No more +1 when shooting at him, *and* he gets +1CR for charging. He's not gonna take down ranked units easily, but that's just a shift in the metagme, otherwise he still pwns.
What I am not sure about is how combats will effect demons. I mean yeah, Bloodletters with S5, killing blow, and maybe hatred, are nasty, but other units will get all their attacks back. 4+ to hit, usually 4+ to wound, and only a 5+ save. They could be taking some serious wounds in return, and with few models won't stand up long.
I can't get a feel for it though, just have to throw down and find out!