I'm currently running MA Silver 8s with an Axiom VP150 center and I like the results. I was fully prepared to change center channels, but I have no plan to do so because the result is not just adequate - it's kick-ass!
In your case, I'm thinking - as a previous poster stated - that the B&W center is pretty darn good and not too different sounding that it will draw attention to itself.
Theoretically, three identical speakers across the front would be ideal, but in the real world how much difference are we talking? Regardless, remember that center channels from every manufacturer most certainly have different frequency response graphs than the mains to which they are "matched".
