I would suggest that you relook at hunters... Take a peek at V's video of hunters blowing through Deadmines. 4 tanks = awesome PVE instance flexibility. And teh DPS is outstanding - mobs melt in front of you...

I also four box and have leveled four (4!!) teams of four each to 60 in the last 70 days. 3 of those were hunters & 1 shammy. (Horde & ally on a carebear server and then another set on Ally on my cousin's server) I find I can blow through any instance at all - and with the new 3.0.2 gorilladin - you can do mad pullz & dps with abandon. Be sure to spec full BM...

I also have very simple macros - autoshot, arcane & a sting. Multishot & a trap for emergencies. And then the buttons that V used to mark mobs & have all 4 pets tank diff mobs. With the new pet talents - you get bonus healing on pets & unless it is an Orange elite (2 levels above me) - nothing hurts my team. Pulled 3& 4 groups by accident in SM Cath at level 39 (many mobs were yellow & some green) and no corpse runs.

It may be just me - but I can run instances much easier with my hunters than with the shammies. The pets give me a margin of error - I run 4 accounts on one pretty decent laptop - but do get lag spikes & stutters a lot - the pets keep me alive through hiccups. With the shammies - I was always racing against the destruction of the stoneclaw totems and I usually leveled up a couple extra levels before trying a given instance. My play style - your MMV.

Just decided I was burnt out on leveling new teams & am blasting through HFP on my ally hunter team that is on my "main" server - primarily because I have the cash for fast mounts & can ignore leveling profs & just blow & go.... Haven't done all the easy gear quests (some of my stuff is level 20 - lol - dang RAF levels you way too fast) & still was able to clear trash mobs in Ramps ok. Again as only a 4 box & just using mend pet for healz...

Enjoy MB. It has ruined my mains - have 4 level 70's that are growing mold & haven't seen more than an hour play time in the last 70 days... MB is just too much of a rush.