Chet (and anyone else):
For someone who needs serious off-axis response in their room, has consideration ever been given to two M2s toed out from each other? I don't know if this would get weird-sounding with someone in the center of the room?
Is your center channel bumped up a few dB, like many people do?
Have you tried going "phantom", to see if your L/R speakers alone would provide better off-axis response for people sitting to the side?
::::::: “Yum. I'd love to gnaw on those with my ears." :::::::