Ken, possibly sushi took you to mean just one M2 off to the side. If you put one up against each side of the TV that would work reasonably well, although it wouldn't anchor center channel info in the dead center. Instead of the mains forming a "phantom" center from their wide-spread position, you would have the M2s forming the phantom center from their narrower alignment. The center image would shift left or right, according to the position of the listener, but wouldn't go farther out than the position of the M2 on that side. Using the mains to create the phantom would allow the center image to shift as far out as the position of the main speaker on that side.
My experience is that a small vertical center doesn't really stick out that much visually.
