I know that questing is faster than AOE grinding, but it's looking like it's a viable way to grind if you are into that sort of thing. NOTE: this is before mind sear (I'm level 56). I have the BoA chest, shoulders, and one hander with +30 spellpower. Sitting at about 290ish shadow damage, which is probably a little high for the level, but I still think it can be done.
Rotation:
VT > Mindblast > full mindflay (this gets you set up with 5 stacks of weaving) > SW: Pain
now, just switch mobs then:
VT > SW: Pain > repeat
The healing offsets any damage you take, keep pulling until you run out of mana. I tried this on mobs a few levels lower than me (otherwise they might not go down with just VT and SW: Pain).
I leveled from 50 to 58 (mostly) on my frost mage in the same area and I can say this is just as effective, fast and safer. Even with 12 mobs hitting me, I never went below 90% health.
The only foreseeable problem is if you don't have enough spellpower to down a mob with just VT and Pain then you might get into some trouble (12 almost dead mobs wailing on you with no incoming healing).
OT: I like questing more it's not so repetive and you always end up finding a quest you haven't done before. But really.. I don't see any problem with you aoe farming, it's a bit more challenging than the regular mob killing which makes it funnier to do.