Thanks Jay, but that is about what I said in my original post about why I did not want to use displacement. Thank you for confirming my original position.

As for AO, I understand that I will get no AO from the bump as there is no actual geometry to be occluded. My concern is that I cannot do a single AO render + bump. It appears the way to do it (and correct me please if I am wrong) is make two separate renders and composite them.

Thanks all for the great feedback by the way. When I was doing automotive surface modeling we did not fiddle with tangent rendering tricks, we just modeled it lol. So I am learning quite a bit and appreciate the input.