Could you not mount the surrounds on the rear wall? I am guessing this is a 5.1 system.

FWIW, QS8's are still the best regardless of position for surrounds, IMO. I think it would depend on whether or not you like your surrounds to melt away or be noticed. The directional M2s allow a person to pinpoint the sound much easier, yet both will do their jobs extremely well. I don't believe you could go wrong either way.

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