I'm using front heights because I'm compromising between ATMOS, DTS-X, and Aura 3D.
To that end, ATMOS does have layout specs for front heights ... I just think ATMOS prefers a TOP layout.

The ATMOS height constrains do fight each other ... they give elevation angles and then also state Heights should not come more then 1/8 into the room.
So depending on your room size, MLP, and screen size your going to compromise.

Anyway, almost have all the Heights and Tops up ...
So, I'll try and take a few pictures and post the HT in progress thread ... maybe today or tomorrow.