Before 3.0 I grinded by saccing a voidwalker and pew pew'ing everything I saw. It took about 6 seconds to kill a single mob instead of ~20 as it used to be as affliction, and there was no downtime because of the health gen from the vw sac.
I have been chaos bolt destro for raiding since 3.0, and I'm considering going back to 0/21/40 with the vw sac for leveling. Yeah, it's only one target at a time, but incin, immo, incin, incin, conflag, lifetap, next mob.
Is there anything I'm missing that makes this a bad idea?