But, my understanding is that you want to get in, do a ton of damage, and get out... if that's the case, again, high capacity seems like a winner. Your heal increase will be fairly negligible in light of a whole bunch of (or a really powerful) enemies slamming you at once, but the higher capacity can help you squeeze through long enough to get out of range if you're really in trouble.
Again, depends on what you want to do... if you're mainly healing other folks, get the emitter array... otherwise, go for capacity. And, speaking of which, rock them covariant shields.
Unless someone comes through with better info, in which case, listen to them!