First off thanks for the info on the M5's dispersion. So if I were to go with the M5's or M3's (in-wall style) in-ceiling how would I place them? Horizontal with the tweeter furthest or closest from MLP or horizontal, tweeter in or outside?
Sitting in the center seat the angle to the in-ceiling speakers is shallower as the distance is further than the end seats. My ears are 3'6" from the floor.
Thanks again for your thoughts.
You have the M5s so you're familiar with their excellent off-axis characteristics. The tweeter is quite linear to about 60 degrees and the mid to about 45 degrees. Beyond that, they don't sound bad but their character does change.
If you place them with their mids 4 feet ahead of your MLP, assuming your ears are about 3 feet off the floor, you'll be within the range of the above angles.