I can't speak for B&W, but I'll give a big thumbs up on the Velodyne. Even the driver engineer at SVS said he was most impressed with Velodyne in comparison to most other subwoofer companies. As far as sizing goes, a well placed, eq'd 12" will sound better than a poorly placed, non eq'd 15". If your room is only (say for instance) 12x14, you really don't need a 15", especially with the power these amplifiers put out. All things being equal, I'd go for the 12" over the 10" for HT and response, if budget permits.