that's a really great bit of info William, thanks! (the dolby document) This is a case where I have a slight advantage being short! heh... I sat in a chair and had my wife measure floor to ear on me.. only 44 inches! So the height from my listening level, to the ceiling (Atmos) is a bit better, because my ears are lower

(I know, its more about speaker height... just sayin' ... )
However... even though this thread was meant to be about Atmos speakers, you guys are making me re-think my whole plan! Once you start down that "what if..." road, a lot of things can potentially change.
I said the seating "has to go against the back wall" - but does it? The idea of pulling it forward initially seem weird on such a small room, but on further thought, it would take a lot of pressure off finding wall space for everything, I could then position a 7 channel speaker layout instead of a 5, possibly work in a 4 speaker Atmos, and maybe, just maybe, use a big-screen TV instead of a projector to get the same perceived "screen viewing size"
I'll have to play around with this idea I guess...