I believe that with the premium B&Ws much of what you are paying for is exotic cosmetics, because they know this sells - and they are right. The cheapest models of B&W offer reasonable value, and in my experience can produce reasonably accurate bass, but too often B&W does not seem to have a handle on great bass reproduction, any more than most manufacturers.
I sold my 805s years ago because the bass was unusable to me, insofar as I could not make valid EQ judgements on them - they were too colored (read "one note"). At the same time, Abbey Road studios was using them, so even the big guys are susceptible to hype, I guess.
As to the notion that a speaker manufacturer making its own drivers is something you can take comfort in, well it has been argued that Dynaudio makes great drivers but can't make a great crossover and, as a result, some of the best performing speakers using Dynaudio drivers were made by other manufacturers. I think it is reasonable to believe that crossover design, not to speak of speaker design in the larger sense, employs a completely different set of skills than transducer design.