Try them, you may like them and that will be the end of the story.
People who love them rave about them. Do listen, because these people have good reason to like them. They are well executed and do what they do beautifully.
That having been said, I don't think I would make Bose my first, second or third piano, if I was to have three of them. I find them unsatisfactory in vast portions of the literature, mostly anything that calls for more than mezzoforte.
I venture people who love them perhaps do not play a lot of Bartok, Prokofiev and Scriabin. Mozart and Schubert come out great, but I (of course opinion) find them wanting even in Beethoven and Bach. I have a CD of Rachmaninoff piano rolls reproduced on a Bosendorfer and that sounds is not wanting, so who knows?
Great connosieurs, like Badura-Skoda and Backhaus, would have disagreed, so take my comment with a grain of salt.
p.s. Alistair, I have played Mason's CC. They roar, as you would expect. Well prepped they are a thing to behold; excellent design. I still like the Steingraeber 272 better, though; more colors available.