morganc, I own the M3 Turbo S. I find I can comfortably sit within 7 feet of the speakers. I find speaker toe in with the M3 is critical. The sweet spot is fairly narrow, so in order to have that center image lock, you will need to be able to toe them in accurately.
It sounds like you may or may not have room for a subwoofer, if you plan to run the speakers close to the front wall a sub would really help with the drop in low frequencies.
I pull my speakers out to 28" (front of baffle to the wall), and slide them back when company is over and listening is non critical. Again, a sub (or two) really help flesh out the pair at lower listening levels.