The biggest issue with the 50/60/80 isn't so much that they have to be placed an ungodly distance from the wall, it's just that they are deeper than most people expect. The 60s are a couple of inches deeper than the 50s and probably need to be an inch or two further away from the wall for the same sound, so figure the fronts of the 50s could be 3" further away from your wife, all other things being equal
If you don't have a lot of cushy wall and floor treatments (do you have carpet / rug ?) then you might find the 50s are a better match for the room acoustics. The 60s are a little more "forward" than the 50s.
Wall mounting would be no problem for the M2s.
Are the living room, dining room and kitchen "all one room" or do they just have passageways between them ?
EDIT -- btw, anyone who has compared 603s with M60s seems to have ended up preferring the M60s. With the 703s some prefer M60, some prefer 703s but the sound is supposed to be pretty similar.
What kind of music will you be listening to the most ?
