I went destruction for Tortos and Magaera last night out of curiosity.
Ended up hitting 95% of the ranking limit on both despite playing terribly, explicitly avoiding meter padding / cleaving on magaera, having affliction reforges and this being the first time I've touched destruction bar that one time in WOTLK PVP.
Certainly seems playable with affliction reforges, sorely tempted to reforge for it and set up my UI / learn what the devil I'm doing next reset - it was a nice change of pace from affliction.
I switch between the two and do well enough without reforging/regemming. My gear isn't top notch but I'm competitive in my guild and with pugs clearing MV/HoF each week. I switch between Destro/Aff depending on the fight. It really just comes down to knowing the fights and what you should be doing and when you should be doing it.