We do it like that only we have 2 mages and a hunter soak them by the time we have to move to the mark for Felseeker all stacks are gone and if melee still have stacks they go stand with the tanks and in the last phase we have the people with it stand at their marks while the raid stands behind the boss and when shadowforce comes they just stack with us and go back to their marks when we get back to the boss, we tried other tactics including the properbird one but they just didnt work for us this tactic is the most effective way of dealing with wrath of guldan.
We started with 4 healers but switched to 3 healers (paladin, discpriest, shaman) and have kept it that way.