When i do Firelands, I tank on my paladin and set my shaman up using lazy raider w/ ShamWoW, assigned myself as the tank and let it go to town healing everyone. It's awesome and works really well and I've had no issues with it. The only issue you may have is knowing that you tank is going to run off and pull, is bout it. At that point your sham will try to follow him.. So when that happens i set the sham to assign himself to following another healer. Using that option seems better because when that healer moves, you'll move... incase of crap on the ground.