Sam, as I've indicated in a few previous posts, I don't care for most horizontally aligned center speakers(haven't heard VP100, VP150)and use a small vertical speaker instead for a center. Perhaps somewhat counter-intuitively, a vertical alignment of woofer and tweeter generally results in wider and smoother horizontal dispersion. The difference isn't huge, but it's there. Your question implies that vertical M3s would be acceptable aesthetically; since the M22s are only about 6" higher, wouldn't they also be acceptable? Three vertical M22s across the front with the tweeters angled toward your ears should work well.
