My new M3 Sapphires are criminally close to the back wall. I'll try and be more helpful in a separate posting, but do not fear overwhelming your room. More driver area, with this speaker, I see as a layman, means less effort. The M3 is becoming super-smooth to listen to, ie not emphasizing anything while revealing the lowest flourishes in recordings. Small adjustments in placement are giving me dynamic scaling and information from within the recording that is just about unprecedented, or is, in my experience... Like the ease and depth and neutrality of resolve of the over built B&W 800D.
P.S. I owned Magnepan Tympani 1D's, and sold (or tried to) Magnepan in Seattle in the mid-00's.