Healing is going to be pretty easy u till you start getting into exs and savage, I don't think as far as leveling goes playing a different healer will change much. Holy spam is fun at least for me just abuse bene, and tetra when you get it, cure 3 is amazing in some savage content, I will say this although I am a healer main I perfer doing main story as a dps because you can use that exp on a dps that would take longer to level due to que times etc and kill your mobs faster, I liked playing red mage in sb story, was able to kill things pretty quick and keep myself healed with vercure as needed, I just dungeon spam on my healers to get them up and that's where you can play how low you can get the tanks hp game :3