Our guild had the same discussion, but we came to the point that DPS was just too weak to kill her in time after essence fades with three healers. So we did it with only two.
Discpriest and Restoshaman, with disc single dispelling (only after anouncing dispelltargets i (restoshaman) dispelled someone => because it might happen that if you dispell wrack at the same time it doubles 1= 3 => 6 => 12 - which is a wipe ). Just use your raidcooldowns like guardian, warriorshout, tranq, hymne, etc. when it comes to the high ticks of 4 x wrack.
- Try a pallytank for the whelps, because he can reset after about 60 stacks.
- Let Tanks pop out CDs on every breath
- Use CDs for letting wrack tick longer on targets (feral or SP is very nice for that )
- In P1 dispell like that: 20s [1 Wrack] (with cd) => 18s [2Wracks] (maybe raidwall) => 15s [4 Wracks] => around 10s [8 Wracks]
- In P3 just dispell like 3 seconds before the breath because this is the critical moment.
- With 2 Healers you shouldn't use Bloodlust in P1 ... you will do it before 2nd wrack without any problems. Instead use bl when the essence buff fades and burn the last 15% or what you have left.