Yeah, if someone has trouble 5-masking as a 570+ BM with GoTT research, then they're doing something horribly wrong. Should be very comfortable indeed.
Anyway, my strategy on Rexxar for those having trouble: Go Drag -> VoH first. Make sure you have Gift off CD because it will hopefully proc when you kill the boars. So you orb, pop a potion, pop drums, blow every cd, use purification protocol when multiple boars come at you, and burn Kekxar down. Drums will be up again for Thrall if you take this route. On my last run with 5 masks, I had 500 sanity, death proc and 1 orb left before Thrall.