"For piston engine work, the Bose Quiet comfort probably won't cut the noise down enough."
Actually, the Bose QuietComfort works very well except in the noisiest of piston aircraft, e.g., C-185, Maule with big engine, open cockpit. In anything else, it is nearly as quiet as the Bose X. The difference in hearing protection is primarily from the difference in size between the QuietComfort and the X. The X is nearly twice the size.
Bose has a 30 day return policy. We recommend you try them in your aircraft... just put them on and wear them. If they cancel noise to your liking, you're set. If not, return them to Bose.
Mike