There is no doubt helmets (may) save lives.
The second last Helicopter crash in Nepal involving Italian registered VIEW an AS350B3+ The Pilot survived ONLY because of wearing his helmet which was totally destroyed following a roll-over to the right after a very high ROD ground impact.
Yet there are many accidents where lives are lost without the helmet saving anyone.
So the choice is the Pilot's &/or the company requirement. For slinging & the likes of working inside the HV area it is a wise move to wear one.
It is apparently another safety step which today is still an option
Which with all the minus's wearing a bone-dome does not guarantee safety, but may increase you survivability (maybe)
Ask Capt. DS (above) he is alive today because he wore a helmet
& then ask Capt. RA who wore a helmet & yet still died in a Heli crash
ask me; unscathed after 2 x engine failures, 1 x tail-rotor drive failure, 1 x wire strike & still here kicking after 23years in the game (never worn a helmet)
It appears most survivable crashes do not require a helmet for the Pilot's survivability, it's only the occasianal odd crash where the helmet did it's duty in saving his/her life
Let the debate continue to rage..................................
Land Happy Always