I had a really hard time keeping the tank up in the final phase after heart with full DL and Garuda weapon. He takes way too much damage too fast. The other healer with me was similarly geared. Once I got my relic it was that much easier. I honestly cannot imagine healing it in my AF gear with a GC weapon. I'd be completely dependent on having the other healer carry me. Same goes for the tank. The damage mitigation with an undergeared tank is just not there to absorb the heavy damage they take after heart phase.