Welcome!
I think that you would see a big boost in front stage performance if you could get a set of M60 fronts instead of the M50s. Maybe look at the "in-cabinet" model since the port is in the front instead of the back meaning that they wouldn't take up as much space as the regular model, but even then you are still .31" too deep. A quandary for sure.
As for surrounds, if you are looking at a greater percentage of movies vs music listening, you will be blown away with the QS series surrounds. They are so good that you will find people that own front speakers from other manufacturers and come to Axiom for their surround speakers.
Just some thoughts.
