This sounds fun & appealing, and I may experiment with the two healer setup once my team is 85. Currently my team is:

Pally tank
2x warlock
ele shaman
resto druid

I have other shamans, and thought momentarily about swapping out the druid for 2x shammy in this team, but then I realized I can just as easily have a resto druid & resto shaman for the 2x healer setup. dps is dps, so I like the idea of two different classes worth of healing spells.

I am curious if a resto shaman does more dps than a resto druid...I suspect it would.