As long as you don't mind dying, and you don't have a healer or fear protection, so it will happen, you'll put out impressive single and multi-target damage.

Warlocks have soul stones and health stones, but you're also lacking a rezzer.

A felguard with 2/2 improved health funnel and the glyph becomes a pretty amazing tank.
With the pet changes on the PTR, this will become much more so.

Any team dies, but Tremor totem and a healer/rezzer is hard to go without.

I did AV with 5 level 60 discipline priests.
A lot of their toys on castsequence.
Sat back behind the action at choke points, and made the other side miserable.
It's a fun diversion now and then, but I don't see myself going through the leveling pain for a 4th team 60-80.

In the end, its about having fun.