I use the Bose X on a variety of aircraft, chiefly the BAe146, but also 737, piston singles (Cessna 152 / 172) and helicopters. They are excellent in every respect, and very comfortable. As a pilot and an electronics design engineer specialising in audio / acoustics, I cannot recommend them highly enough.
Loose rivets, did I meet you at the Wolfson Centre, Essex Uni? I did postgraduate research in acoustics, resonances and echo deconvolution with Prof Malcolm Hawksford next door in the 1980s, and knew Owen Jones and Mark Trinder who were the proponents of noise and vibration cancellation there at the time. The noise cancellation that the Wolfson Centre specialised in was on a far greater scale, using an array of KEF B139 drive units around exhaust stacks for big diesel engines, driven by up to 1,000W of power amps. The Bose seems to be a perfect evolution of such technology, with its beautifully applied technology, running for 40 hours on a couple of AA batteries.