Difficult, yes.
Efficient, not so much. It's the same concept of learning the fight with RDM/SMN for Rez utility during prog and switching to a BLM for the extra DPS once it's on farm. If you can get away with dropping one or both healers to clear content, there's no reason not to other than having that extra safety net but that's not a matter of efficiency, that's a matter for peace of mind more than anything.