Great setup. Those alcoves for the speakers/sub might pose some significant bass management issues have you considered adding bass traps in the corners at the back of the alcoves?
I see the fronts of your speakers are brought forward from the edge of the wall- so edge diffraction should not be so much of an issue...nevertheless you might get a better imaging withe the speakers forward a bit more.
Strictly speaking you should close the gap between the frame and the center channel (make sure no gap) - a picture frame sometimes works well - a gap will give you edge diffraction issues and reduce the imaging.
I really like this room and setup...it looks awesome and that 71" screen has me drooling!! I hope my suggestions are taken in the spirit they are offered...just passing on some experiences...suggestions only and no criticism intended on what is one of the more impressive HT setups on A'gon. nice job.
