Rear surrounds can be a personal preference thing. Some say for multichannel music, bookshelfs work better, but those that have the QS8s and listen to multichannel say it is still very good. For movies the QS's win hands down, IMO.

I used a M60 as a center for a weekend for a comparison with the M22/Vp150, before sending them back in favor of the M80s and I must say if you can fit an M60/80 as a center channel go for it, it is by far the best sounding front sound stage I have heard.

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