I reforged everything to haste. With full wrathfull being my pve gear, with a pve belt, rings and trinket. The logic behind it was quite simple for me. The difference is that I hardly do pve. Only farm HC's for JP's. So if I cast more then 2 spells, something is dead. Overload really adds hardly any effective damage there. Because i will always have to cast 2 spells.

Of course there's the odd case where it might be just enough dmg from fire nova's + CL etc that a target get's killed by an overload but yeah. If you're aim is raiding then mastery is probably best yeah.

Besides that haste effects healing aswell, for what that's worth :P