Dave--
I'm coming from experiences I have had on the track where chunks of rubber and other debris thrown up by cars immediately in front of me have hit my face mask and on a couple of occasions left scratches/gouges. Driving with windshield down on roads at 50-60 mph would be no different. Yes, the feeling of wind in one's face is cool but is it worth the chance of losing an eye, etc?
Michael, So am I.... I raced mine for over 15 years (99 entries in my log book) with a small Perspex shield that I look over, not through and I know just what you are talking about. But it is nothing like that on the street - there are no chunks of ground off rubber to kick up and you are never following someone as close as we do on the track - and usually when getting hit with debris on the track it's in spots where folks in front of you drop a wheel off and catch some gravel, again, not a common problem on the street.
I also rode motorcycles for years before we had helmet laws here in Washington State and I loved every minute - lost my interest in riding when we got a helmet law.
As to eyes - I use OSHA approved safety glasses (look like regular sun glasses) and I am not in fear of damages to my eyes. Worst I've suffered is from hitting a bumble bee at 80 - dead center in my forehead, was very messy.
I chose to not be afraid of fun things and there aren't many things I think are fun that aren't dangerous. I had my first windshield down ride in a 100 in about 1965 and that experience sold me on Healeys.
Are there risks with the shield down? You bet, but there are risks racing too and I know lots of folks who think people like you & me who race are crazy to take that risk, but there we are - racing at every oportunity.
Dave