Personally I would stick with just M80s/VP180 up front and QS8 surrounds/rears and heights if you use them. Onn’s opinion might differ since he has at least 4 M80s but IMO comparing the QS8s to the M22s (the M80s little cousin) the QS8s win easily in the surround role and win slightly in the back role.
Though I’m not a sound engineer from what I can tell there isn’t a lot of low frequency information mixed into the surround and rear channels and considering that engineers probably mix for what the expect the average person is going to have in the way of speakers I don’t think they will be putting lots of lower bass in the surround and back channels very soon. Might be wrong though.
If you were to add wide channels I would stick with M22s or even M2s.
IMO you might be better served by upgrading to a receiver with wide and or height capability and adding speakers for those channels. But it depends a lot on how your room and seating are laid out if this would make a big difference or not.
