This subject seems to continue across forums with threads galore, everyone seems intent on expounding their opinion regardless.
I've been knocked unconscious during an accident because I was daft enough to go low level filming without a helmet, in a bog standard Bell Longranger. I wouldn't dream of ever going into a higher risk flying environment without a bone dome again as it hurts. As a further example, all our fire agencies in Australia mandate helmets for all crew in any aircraft be it a Firebird stoogeing around at 5,000ft or a Helitak down in the weeds.
FWIW, having done EFT on the Chippie and a few hours to contemplate the cockpit hazards, I'd consider a helmet a sensible option when flying it but wouldn't be critical of another pilot who chose a headset instead.