yeah, i just thought my 5x warlock team ruled the 0-60 dungeons. I was unstoppable... then came the outlands. They can't take any boss anywhere.
There isn't a single outland boss that isn't completely immune to all types of fear and horror. All of the bosses seem to have special warlock pet killing powers.
I got them to 70 but I pretty much gave up on them. Durn would do an AoE that wiped all of my pets at once and then proceed to wipe my team all at once.
It was cool to see the warlocks get all of the DoTs going, 25+ dots look awsome and most items can't survive long enough to get more than a few of them going.
I rolled shaman and they smoke Durn without even having to cast a single heal, the don't have too many problem doing all of the dungeons. I do SV, SL, Mech, Bot, etc.
The shaman don't do as well as locks for crowd control but they eat bosses.

for Durn I drop totems and 5x earth elementals, cast heroic, cast trinket and just LB him to death. The elementals seem almost immue to is AoE.