At L75, I have been able to clear all of Drak'tharon without too many problems.

It is definitely worth farming the first boss until you get Troll Butcherers (2H Sword) for all your guys. It's a pretty good weapon, if you don't have better.

I could clear Drak'tharon at L74 with the hunters (and my druid at L72). It's easier now at 75/75. Nexus runs are still best XP/hour since it's total autopilot and I can just steamroll one pull after another. (Due to my inactivity in-game for a few weeks, I'm sporting full rest XP though).