I thought Malgus was pretty useless as both tank and healer even on live. He can't even heal himself properly, and as a tank he doesn't mitigate very much so he usually ends up dead from all the aggro he pulls. So just put him in DPS stance and let him do his thing -- wreck face. Yes, even if you are DPS yourself. I had a much easier time going through the temple as a DPS pair than as any other combination.

He seems to be a special case though, as his abilities don't change all that much between stances, if memory serves.