The plan (so far) was to upgrade the M80's to something newer, move my QS8's to the side wall for surround sides and move a set of on walls to the surround back channels.

Are you saying the M2 and M5's are a better speaker than the M80's with the larger cabinets and more drivers how is that even possible?

VP180v3, M80v2, QS8v4, Arcam AV860, Rotel RMB1585, Epson 5050ub