Depends on your GPU Power. Used to run two GTX470's in SLI with it on, and then a GTX580. Now I have two GTX680's and I know it can handle it, but the drivers just aren't optimized for the game.
I haven't had a crash since turning off AO and DoF. I still get the random what the hell crash related to the server, but not my game losing communication with my GPU.
