Had 20 minutes with the H6 yesterday.
First impression is that they are light and well built, isolation is good and comfort is excellent, definately one of the most comfortable closed headphones I have tried in recent years (and I've tried many).
Sound is typical B&O, not that exciting, quite neutral, but a little boring. Bass is not very deep and there's not much of it, treble is nice and not harsh, so overall it's a pleasant sound.
If it was half price, it would be a...