I've played with the thought of this setup:

2 shamans, 3 druids.

1 enhancement shaman for the naturedebuff of stormstrike
1 elemental shaman for spelldmg totem+ crit/hit totem
2 moonkin druids for spellcrit aura and nuking
1 healer either resto shaman or druid.

Maybe swith one random for a beartank when needed, but that makes the enhancement shaman harder to control.