I think the M2 center may just give you a little more vocal clarity for movies. Once you get them you can try one M3 as a center to see if you like it there as well, if you do you could send the M2 back (or keep it for use else where) and get a 3rd M3 after a couple of weeks. As this would be an upgrade I believe Axiom will pay the shipping charges.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70