I run gosac for everything I use destro on...exception being if I'm playing destro on h.thok where I'd use the imp for extra raid (mass) dispels but that is a case of utility > damage. Also since you get to cast less a pet helps. Though most of the time I'm just aff (also w' the imp for dispels). Especially if you have heroic ilvl and/or have a KTT gosac just beats everything else. If you find yourself clipping chaosbolt's dot then adjust your playstyle slightly.