Hello Pete,
The great part about the NANOSAT prestiges is that you can be very close to the speakers without them starting to lose their enveloping sound field which is so crucial for good surround sound systems.
However, I just recently moved my NANOSAT prestige's from my end tables to the wall (about 7ft high 1ft below the ceiling & 3 ft from the rear wall). Even though it wasn't a night and day difference, I prefer the new set-up as it appears to give me an even more enveloping experience than the previous set-up. It also helped to stop my 3-year old from using them as little "footballs"...
By the way, I use the NANOSAT prestiges as rears with OMD-5s in the front and the new Prestige S8, which turned out to be a great system.
Cheers,
MTF