Hmm I've had this discussion too. My 2c worth - although I don't wear one myself I think it says something that military pilots (professionals for whom fashion / pleasing customers is not a top priority and H&S is) do. Now purely anecdotal but the only accident I've heard of (and I've read quite a few) where someone was killed through wearing a helmet was, from the hazy depths of my memory, a guy killed when in the crash he was thrown clear from the cockpit but was asphyxiated by the cord between his helmet and the a/c. A squirrel by a lake - Scotland I think? On the other hand I guess attributing a cause of death to singularly that a person was wearing a helmet would be difficult in most fatal accidents.
My personal view: I'd rather wear something that'd protect me in a relatively minor accident; dynamic rollover, PFLs gone wrong, that kind of thing, and take my chances with a broken neck in a midair or CFIT with their higher deceleration forces but which are probably less survivable anyway. I'll never forget a story of a FW instructor in Florida who had a theory about not wearing his seatbelt; in a low speed crash he could just hold to the yoke, and in a high speed crash he'd probably die regardless of the seatbelt. Then one day his engine failed... the student flew the a/c to the ground while he had a change of mind and decided to put it on after all...
