That's hilarious, when I'm running as Bard and see a healer DPS'ing, as long as there's no reason to the contrary (such as them not covering their primary role responsibilities like healing and mitigating damage and removing debuffs) I'll use Foe Requiem to get the most mileage out of their MP invested in casting damage dealing spells, and swap to a Ballad to fill them back up a bit if needed. And the healers who truly are effective at both healing and damage dealing already knows how to manage their MP (if they don't, then they're not a very effective healer) so it's not like I'm taking a DPS hit keeping Ballad up much, if at all, when I'm using my Bard MP to enhance Healer DPS. Better than letting it go to waste like most Bards these days.

I remember a run where the WHM and I were in perfect synch, when she went into cleric stance I'd kick off Foe, and then deactivate it when she turned off cleric. It was like we had our own dance going with each other, while still hitting the all the right steps within a bigger choreographed piece.