I noticed the old units were still there, and I ignored them. I don't want spoil you, but some of the new ice devils start off with very nice magic items. I've look through the spell list and I see no good way of dealing with an Ice Devil with any spell below level 7.
If Ice Devils were a level 6 summons they would still be better than any non-blood summons. It's possible that my dom 1 experience taints my analysis, and when the full game is out it'll be no problem. Looking at the stats, however, I don't see it. I suppose we'll find out soon enough.