Actually, I noticed that too with a group of four - the affixes are tougher - and I think this might be a fairly recent change. Even in Act 1 I get some crazy mobs, reflect damage, molten, invuln, frost, plagued or something crazy.

I can do pony runs on my WDs, but I usually die - I basically stand there and aoe and let the LoH heal me. I kite the elites to the entrance so I can respawn quickly and they don't reset.

I recently leveled barbs to 60 - man, what a waste. I can't believe I tried that, the rage crap is just too much to deal with.