If you think of where surround speakers are supposed to be set-up, the sound on multi-channel audio discs is really not supposed to end up in the rear channels. And you're right, it isn't really supposed to end up in your side surrounds. Uhh, now I see the problem.
I have heard that the rear surrounds actually can work very nicely as bipole speakers. If your side speakers are switchable, which many multi-pole speakers are, you may want to switch them to bipole and make them the rear surround channels. That way you can use the monopole speakers on the sides which should probably give you the best sound for both movies and music.
You can always swap out the speaker cables, but that's a pain. Umm, I don't believe there's an internal way of switching it, but I don't own a 950 so maybe somebody else knows.
You have a raised, at least in my mind, a nice little quandry. How do you get the best of the 5 plus speaker modes yet still maintain a speaker set-up that benefits multi-channel audio? I know, before they even post it, use Logic 7. How about if you don't want to do any extra processing??