My team just dinged 74 and my Gorillas are now 71.5. So far, I'm impressed. They seem to hold aggro much better than worms, though my dps suffered just a little, perhaps due to the pet level difference more than anything else. I haven't attempted any bosses in The Nexus or UK (want to ding 72 and get another talent point) but we'll see how that goes.

As for healer, I'd guess Priest, Druid or Shaman could all work, though I have a bit of a bias towards Priest, mainly because I know how to play that class better than the others. I've grown quite attached to PW:Shield, PW:Fort, Fear Ward and Prayer of Mending. Plus, a glyphed Prayer of Healing is quite powerful and great to top off health bars during trash pulls. I must admit I'm jealous of the Shaman wipe-protection and the Druid AC, but so far the Gorilla aggro generation has kept mobs off my squishy self. If that holds, I think a Priest becomes a clear healing winner.