Cure VI is for those moments you need to cure two people for massive HP. Cure V's recast is not big, but it's just big enough that it there will be times when you need another big cure RFN.

Still it's too expensive for it's cure power. And healing raw HP isn't the problem now, its the status ailments. That is why I said give WHM Erase II and a JT that makes their regular cures randomly remove a status ailment. VWNM monsters use moves that inflict 2~4 status ailments on everyone around them. Even with a WHM, RDM and BRD spamming erase it becomes nearly impossible to keep them off the two PLD's all the time.