I use an A20 in a radial Pitts. I had heard Chinese whispers that the A20 simply wouldn't handle the noise reduction in a loud radial, which turns out to be nonsense. It handles it fine.
Also I accidentally sat on it one day and snapped the headband, making it unusable. I called Bose and admitted it was my fault & asked if I could pay to have it repaired. They said they'd repair it under warranty anyway, sent a courier to pick it up, and had it courier delivered back to me, together with a bluetooth module upgrade to the latest version, and all new ear cup padding, mic muff, etc.
Nothing but positive things to say about them, or the service.