I did around 7 years in BN-2A, wearing nothing but (passive) DC-H10-60's. Absolutely no measurable loss of hearing either during or to date. Sure, they're noisy, but nowhere near as bad as some in here would like to make it seem. Damn fine wee aircraft IMO.
For any airframe, I'm of the opinion that the best protection for your hearing will only ever come from your own, personal headset, that only you have ever worn. My headset is to me a very personal item of kit, similar perhaps to a toothbrush. Only ever used by me, never ever loaned to another.
'Communal' headsets will provide some benefit, but the best will only ever come from your own.