Ya know, I could almost have offered an A/B on M3s VS M50s.
But we moved to this acoustically challenged house Before I got my M50s.
My M3s imaged beautifully in the old house; I could almost tell the color of the dresses worn by accompaning singers on a favorite CD!!(The M2s and M22s may be even better, but I'm not sure if the x-over is in, or out of the vocal range on them, as it is on the M3s)-not that voices are the only criteria, of course!
I don't know if it's fair to say that the floor standers fall flat, but I believe that it's generally recognized that mini-monitors with their reduced baffle area and relative ease of optimal placement give them an advantage in imaging. That, and the reduction of room-induced bass mucking due to not having a lot of bass to have to account for in the room layout that may be virtually uncontrolable, but that can be corrected with the use of a good musical sub.
Unfortunately, in a large room....
I did, however do a test with lots of pillows and throw rugs and furniature repositioning that allowed my current listening room to, at least temporarily, give a pretty good accounting of itself accoustically-if only for one evening, and was able to assertain that my M50s do actually do an admirably reasonable job of producing a fairly accurate soundstage with more than acceptable imaging!
Unfortunately my listening room in that configuration was "Unlivable" by WAF(or any other reasonable)standards!!
