I don't use tanks anymore.. I have 2 Destro locks which do awesome dps along with a survival hunter.. all 3 pets are tanking, my Druid heals and I also have an ele shammy.. I'm considering replacing her with another hunter though.. her dps is bad compared to the others.
2 locks 1 hunter 1 druid 1 shammy = 3 dps; 1 possible tank; 2 possible healer

with

2 locks 2 hunter 1 druid = 4 dps; 1 possible tank; 1 possible healer

you can't LFG anymore because of the missing tank or healer because
your druid can't fill both slots.

that's currently my problem with a priest + 4x WL setup - I can't LFG
because I don't have a tank