Like Ghishlain said, Brayflox is the first real dungeon (imo) that tests both healers, tanks and a few dps depending on class. Cure II is really just Cure I but with a faster cool-down time and at later levels you'll see that Cure II was has same mp cost as two Cure I's so I'd suggest using Cure I unless you know that it won't fill the tank to fill, then I'd use Cure II. Also at level 35 you unlock regen a HoT (heal over time) and a god send (imo) of a move that really helps with healing, but be careful not to use it when the tanks pulling the mobs, because it does generate aggro.