Heroic: Heartbreaker Impossible? (LF Blue)

First off, this is not a "NERF HARD MODE" post. I am the last person who wants to see the challenging areas of this game nerfed.

That said, I am wondering if anyone knows a feasible strategy for XT-002 Hard mode (in heroic).

At this point, it seems my guild needs to pop heroism in order to kill the heart. Is it possible to kill the heart w/o heroism, saving heroism for the massive amount of HP XT gains?

Also, about the time we kill the heart, we have about 8 minutes left in enrage. He has 56 million HP. If we assume 1 tank and 7 healers, that leaves 17 dps.

56,000,000/8/60/17= about 6800 dps per player on XT-002. However, this does not include the DPS the ranged has to do on the adds, and downtime from getting gravity bombs. Am I missing something here or is this encounter not feasible?