I used to run Pally (tank), mage/warlock/shaman (dps and priest healer.

I swapped out the priest for a druid and never looked back. Druid healing is ridiculously easy. I have wild growth on a click sequence tied to my dps button and use a repeater region in ISBoxer for manual healing. I'm over geared now for most heroics, but I hardly have to actively heal with the super fast refresh of WG. Its virutally 100% up.