On my other teams (5x Tank Pally and 5x Afflication Warlocks) I won't worry so much about healing. Though, the pally group do occasionally need to heal but with all 5 throwing out a single small heal it works out well. But with my all Druid team its not as simple.

I tried 5x Boomkin but that failed at higher levels so I went to the trinity group. I've been using repeater region for the healer and the whole team can throw HoTs on the tank in an emergency but as has been pointed out by the OP its going to be a huge problem come Mythics.

Based on Mad Milita's advise I implemented GSE for DPS only (yet to use it for healing) and its make a significant difference to my DPS! I'll spend some time next week and reorganise my setup for GSE healing.