I have a group with 2 druids, 2 shamans and a hunter (I always like a pet for auto off tank). I tried to work with one shaman for heals and found it hard. Switched roles (now 2 ele shamans, druid tank and druid heals) and all became much easier. Not sure why, but I think its the hots. I still have the shamans defined in my heal group so I can add extra heals if required. If my tank gets in trouble I entangle, put the pet on the mob, tank drops some hots on himself, and away we go.