Some thought provoking responses; thanks.
I believe I am at this point going to invest in the expensive, but supposedly world class noise diminishing Schuberth pro helmet. Combined with foam ear plugs at 32 dB reduction they should provide substantial protection.
As regards riding, perhaps it is my inexperience, but I would believe that your eyes will save you when riding, not your ears. My philosophy would be that I must see literally all that is going on around me and never rely upon hearing other vehicles. I would suspect that sloppiness and casual lane changes, etc. would creep into driving habits if I thought I could "hear trouble" coming.
I believe that if I know I have reduced hearing I will be more dependent upon my vision and not slack in terms of looking to be constantly aware of my surroundings. If I'm wrong, I guess I die.
Seriously, I would rather wear a helmet and ride with the disadvantage of diminished hearing than to ride with no helmet and hear more noise. I do not believe that the ability to hear approaching vehicles would be improved without a helmet, as the noise level is so much greater.
Anyway, the discussion is good here. In the not too distant future I may migrate to a more substantial bike with faring and larger windscreen. I was hoping the new Honda CTX would fit as it has a flared front to block wind, but it was dinky, not a hope of my riding it. I would have to get into a larger sport touring bike.
I will be very curious how the noise reduction goes with the new helmet. Ponying up four times the cost of my first helmet, it had better be good! I believe that if the noise is not much reduced, then I likely will be forced to look for a different bike/design with a lot more blockage of wind.