it helps an enormous amount. Okay that's understating it. Having a SBR/SBV set for anub arak almost trivializes the adds in terms of survival. Don't get me wrong, dps, and positioning is still very intense, but if you want to make your attempts easier by eliminating one of the hard parts of the fight (add tank death), an sbr/sbv set will help a lot.
it can be done without though by having 3 tanks, and each tank splits 2 adds each, and positions them in such a way that they can be aoe'd down but not close enough together to haste each other.
think of it as
OT BOSS OT