In my job I have to wear a helmet it's the law but I am not worried about the accident bit and therefore saving my bonce but more like saving my hearing thanks to the better insulation against noise for the whole of my head.
As for the Scotland squirrel crash I have heard about that one as well and I seem to remember what killed him is the lead which got caught on something in the aircraft and therefore pulled his head back. Since then I have made sure my lead can easily unplug if I were to leave the aircraft without unplugging the lead first. We used to tidy the lead away by draping it over the wander light but I have stopped that now for that exact reason.