Yes, I've run with no center speaker before. The 970 has a mode that allows you to mix the center channel to the left and right mains in varying degrees from all center to all through the left and right. It worked great and the center channel sound came from dead center of the TV while you were in the sweet spot. However if you're not in the sweet spot the sound definetly panned either left or right which I found more annoying than having the center channel above the TV (in my case). I switched back to the center channel config.

Another drawback of the 970 approach is that it could only perform this function when using the internal digital processing. When I switch to 7.1 analog mode for my bluray I lost this capability. Your approach of running the monitors in parallel sounds like it might work. I'm not certain where the best location would be to place them though. You'd have to experiment.