This post is a bit of shilling.
First let me say that I know the QuietComfort2 headphones are nice because I've had a pair for around three years. I work with them on frequently, I travel with them all the time, I use the heck out of them basically and they're much loved.
But they broke on a recent trip, and that reminded me of another feature I like about them: support. Bose replaced them for me (3 year old headphones!!) with a new pair for $50 ($50!!). If you haven't bought them because they cost a lot (and they *do* cost a lot) you should know that you're going to get a set of headphones that will last and last, and if they don't, you'll be able to get a new pair without taking out a loan