After trying unsuccessfully to run 5x balance druids, I am now switching over to 5x bear tanks. The advantage being that I can sub out the lead druid and use my heroic raid geared main (a bear tank also) who takes almost zero damage from most 5 man mobs.

The gear will be uneven though and I suspect that will offset the advantage of being able to bounce aggro between 5 similarly geared bear tanks and gaining sufficient rage and vengeance on the others.