One of the things I've noticed, for me anyway, about B&W speakers is that like many audiophile speakers they are voiced to exaggerate detail. There are several reasons for this, from frequency response decisions emphasizing the presence area (upper mids, lower treble) to issues with the rigid drivers B&W likes to use generating subharmonics and self induced noise. At first blush, this sounds kind of exciting, why, listen to that, I never heard that before! To my ears, however, after a very short while this sound becomes tiring, I tend to get listener fatigue from a lot of high end speakers that I never get from B&O gear (or things like old Tannoys for example). Your ears may not do the same, but it's something to be aware of that doesn't show up in a short dealer audition. Something to consider before dropping 70k+ on a setup!
I've seen similar things happen when people swap out capacitors in crossover networks for whatever the latest, super duper film cap or such of the day is. Often these caps, when compared to what the designer chose, particularly if the designer used standard electrolytics, have less insertion loss/series resistance than the lytics. The result is a small shift in crossover freq, but more importantly a shift in loudness of the driver attached to the cap, usually mids and tweeters. Perceived as an increase in detail, it's actually changing the target response the designer worked very hard to achieve. You may like it better, you may not, or as is often the case you may like it at first then get tired of it, sell the speakers, get another pair, then do the same to them! 😁
