Ray, i have my QS8s sitting on 1" rubber feet so yours have more clearance than mine. I have not noticed an overly large difference between my left surround which is wall mounted and the right surround which is on a shelf. Since the walls and rooms are shaped differently, i imagine some of the sound difference it also coming from different reflections.
The sound dispersion is still extraordinarily convincing.

"Those who preach the myths of audio are ignorant of truth."