There is no advantage CNJ would give you over using WHM and just us making more use of Cleric Stance, maybe even a bit of Holy spam to help burn down those heads and stop the raid wipe. However you elected to play a non-optimal set up and somewhat succeeded based on skill. However you still gimped yourself and could have potentially saved that run, but chose not to have that option available.

Sometimes one person CAN make all the difference, I know because I've saved a few runs myself with a miracle heal or well timed stun. It's not always about personal performance but what you can do for the team as a whole.