Keep in mind that I am currently using two M2i's for surrounds. I used to run a 7.1 when I was stationed in Japan but the current room I am in now doesn't allow for the additional two back placements so only running a 5.1. With the M22Ti's, VP100 and the M2i's, sound has been acceptable for all of these years but my hearing has declined and of course have decided to upgrade. Adding the M60's and the VP180 will substantially improve front sound stage. I would think, any upgrade to the surrounds at this point, even if just upgrading to M2V4, would be an improvement. Honestly, I am not looking for blow my head off sound lol. Just more volume and and great quality sound.

M60
VP180
M2i
Sony STR-DN 1080