Hi Sylvain,
No--at least not in most rooms. The M80s are direct-radiating speakers; the QS8s radiate in four different directions, so they deliver a rich mix of reflected sound, yet retain a surprising amount of directional acuity for effects or music "hard-mixed" to a particular surround/rear channel.
In really huge rooms (8,000 cu. ft or larger) which have lots of reflective qualities--cathedral ceilings, lots of glass, and the like--the M80s might produce as enveloping a soundfield as QS8s, although I really doubt it.
Regards,
