Chris, I think most people will tell you that you should have a center speaker that is vocally/sonically matched to your front towers. That makes intuitive sense.
However, it's your money so it's up to you and your ears (and your wallet). I personally have been using a center that was not even built by the same company as my towers and it never bothers me. Just depends on how critical you are with your listening. If I were in your position, I would err on the side of tonally matching your center with your towers by buying a center from the same company and the same product line. B&W should be able to tell you what center speaker in their lineup is the best sonic match for your towers). But, in the end, do whatever makes sense for your situation.
