It seems that they could just divide the array of surround speakers in half if there isn't room on the rear wall. The front half of them the surround fronts and the back half as the surround rears. As long as the sound engineers understand this when encoding the master, then it would add a depth to the rear sound-stage that wasn't there before, especially with pans from front to rear, or doing circles around you like in Spiderman 3. These types of pans are not really conveyed all that well in the movie theater since the surround speakers could be 50, 100 or even 200 feet in length. I remember seeing Spiderman 3, in the scene where the Sandman is created, at the movie theater and didn't notice anything at all that stood out in that scene sound-wise in the theater. But, when I watched it on Blu-ray at home on just a 5.1 Axiom set up I was blown away. It can almost make you queasy by how great the sound effects were made in that scene.
