Looks like your front soundstage has matching LCR speakers. Are you using the same for your surrounds? What's the make and model?I have wanted to do and in-wall installation in my room but I have some acoustic challenges (mainly a support pole) to deal with and was afraid to commit to cutting the holes.
Since our theater is pretty small (12'x16'x 7'ceiling) I'm using 4 Triad bipole surrounds. Two at the rear and two on the sides. I'll also have some custom made diffusers next to the surrounds to make the room sound larger.