The suggestion is to build a portable frame for the cabinet. You see the incab's have the front port so you don't need to worry about them being right up against the wall. However if you build a portable frame you could do all of the angling you wanted. It's the best of both worlds in my opinion.

My Stuff :

M80's
QS8's
VP150
EP800
Denon 4802
Emotiva XPA-3
Samsung BD-P3600
Sharp 65 Inch Aquos LCD