Nick, I had my QS8's mounted on the rear wall (against which rested my listening couch) for a long while. It was fabulous. We subsequently reconfigured the whole house, moving the theatre to a different room. But I was quite satisfied with the surrounds positioned flush with the rear wall. I had them about 2-3 feet above and also about 3 feet to the sides of the couch. I think the flush-mount T-bracket supplied with the speakers makes for a clean and elegant install.
In your case, I would certainly not spend a lot of time or money on alternate mounting methods.
Just my $0.02.
