"If God forbid something did happen to him I think I could live with no regrets".
"...live with no regrets." Hmmm...did you buy the protection for your son? Or for you?
My son turned 18 one year ago and we (my wife and I) let him buy a bike (95 Katana) with the stipulation that he pay for everything himself and take the rider safety course. He did. He bought gloves (required for the safety class) and already owned a helmet (we snowmobile). I bought him a jacket with armor. When we ride we pretty much wear the same gear - armor jacket, helmet, gloves, and over-the-ankle work boots. He's a good rider but everytime he goes out I still think about all the things that could happen. Then again, I think about the same stuff everytime I get on the bike. I guess we could both be safer, but if I really want to be safe I would give up riding and sit in a rocking chair until I die (not likely).
If you really want your son to be safe tell him he can't go. Then buy him a rocking chair - with a seat belt and an air bag. That'll teach him to be scared of living and cheat him out of all sorts of fun experiences - like motorcycling, riding in a car, cutting with scissors, drinking hot liquids, eating at Taco Bell, etc.
On the other hand you can let him go and (probably) have the greatest experience of his life (next to having you as a father of course). Just make sure you explain the dangers and how to be safe (includes wearing aforementioned gear). Then trust God and your father (or is that "God your Father?") to take care of your son.
I'm guessing your boy will be in pretty good hands because it sounds like your dad did an OK job raising his son. Right?
By-the-way, your son will probably only use the type of gear you wear. Or only the gear your father wears. Your dad doesn't ride in shorts, sandals, and a ball cap does he?