Definitely not a dps race. We 3-heal it every time. We even let him heal a bit last night because one add was just outside of null barrier, and still killed it in reasonable time.
If you have a druid, have them spec into Ursol's Vortex and drop it right on the group where the adds spawn.
If you're looking for a good benchmark, you want each phase to last no longer than 4 casts. First Velocity (bubbled), second, third (bubbled), fourth... move on to Shadow.
Nullify first, DPS second, nullify third, DPS fourth
Nullify first Epicenter, punch 2nd, N 3rd, P 4th
Pop heroism, kill Fire in 3.
We 2 healed it on all our kills, and we don't even stun the earthquakes. There's not actually a lot to heal besides the high tank damage. Most of the boss mechanics can be taken care of with a raid CD or the barrier.