Just my 2 cents
The "older" heroics, when in badge gear as of now are cake. My pally can do entire heroics without getting healed at all and he isn't even that well geared. Its the newer Hor Pos Fos that WILL give you trouble if pve content is on mind. Anything is possibe though!

As for the locks this is a question I'm tossing around as well as confronted with a choice of 5 locks or 4 with a priest. Think I read somewhere that the priest is just a weak spot to be hammered in pvp. Does anyone have a solid viewpoint of 5locks? Been using shams for awhile now, itching to fear a few people myself for once