AO as is now, killing your FPS it's not worth it.
it does give a slight difference, but none that is worth it dropping another 5-15 fps for.

as for DoF, yes for those that can run stable with it it's worth it.
i'd still rather have a clear sight, but then again, with the textures blurrying out in the distance DoF surely does give a better view.
with General Drawing Quality and Background Drawing Quality both at highest the view with DoF is at best, but setting both on highest really drains your GPU.