Well, I started flying the Legacy just recently and some of our airplanes are equipped with Bose headsets. The reason for this is the apparent higher noise level in this cockpit. Most other jets that I know do not need a headset - at least during the cruise portion of flight.
I must say, they're unusually quiet.
Coming from F2000s and the CE750 where cockpit noise is not a factor, these active noise cancelling headsets make me wonder whether the engines back there somewhere are running at all (the only hint during engine-start is the gentle shaking of the entire airplane). This is unusual. But hey: they're working and doing what they're being paid for.
In my opinion probably just perfect for a turboprop, chopper or piston engine airplane.