Block is SOOOO important in the latest patch. Not only for HC, but for SC also, since you can't kill things very fast when you're dead.
I just made a max block sorc, and she's level 81 now, and she has 1k life and of course max block. In most area's she can tank for her own Meteors though she does use a Merc too. He's just around for the occasional Fire/Cold Immune which she can't kill.