I'm fortunate enough to have a v8 and occasionally rig up a 7.1 set up. When I do so, the most interesting things for me are listening to 2 channel music through the various DSPs, esp Trifield (uses sides and rears)(and DVDAs of course). I think Skyfall is 7.1 but the effect of a 7.1 setup is fantastic with 5.1 and lower movies.

Personally speaking 7.1 out is the thing, if I only had 6 channel in, I would be very mildly disappointed. I know that's not the point of the comments, I'm just adding an observation.