"Leaving the aircraft without unplugging helmet"
There was a post on here some time ago (in association with the squirrel accident in Scotland i believe, I haven't found it so far) where a contributer had thought of the accident scenario and came up with a solution.
A short (about 10-15 centimetre) lead with another set of plugs was used to create a weak link that could adopt any angle and allow the user to disconnect from the aircraft. He'd had no problems with unintended disconnection because of the length, and although he'd not had to use it for it's intended purpose, he was satisfied that it would work. I thought this was such a great idea I went down to my local avionics engineer and now have a weak link in my flight bag.
The reality for most of us that the most likely advantage from wearing a helmet will be that we can hear our wives (or husbands) moaning about how we're under their feet after we've retired...... For those unfortunate enough to have an accident, hopefully we'll never know how bad injuries can get, which to my mind makes them worth their weight in gold.