At least one of the fellows here (JohnK, I believe) prefers, and recommends a monopole speaker (such as the M3 or M22) as a center channel speaker. So, it's not out of the question. Most of us use the conventional centers (VP100 & VP150). I do, so I don't feel qualified to comment.
As to your other choices, it helps to know the size of your room (WxDxH); how far from the speakers the listening area will be; your speaker configuration (5.1/6.1/7.1) and what you listen to (i.e. 50% music, 50% movies; are you interested in SACD/DVD-A; etc.)
