Plus it makes no sense to wear a helmet to protect your melon and then put sunglasses on that could poke your eye out if something were to happen.
Huh? That statement makes no sense to me.
If something is happening during a crash where it is penetrating the helmet enough to touch the sunglasses, then I want them there for additional protection.
Besides, when was the last time anybody saw any facial injuries from a crash to a rider wearing a full face helmet?
Many members of my family are opticians.
I've seen some MANGLED glasses from very light impacts (non-motorcycle). I don't think you need to worry about objects destroying your glasses. The thing i would be concerned about (and am, I only ride while wearing contacts, not glasses) is your helmet moving around, dislodging, etc.
I've tried wearing my perscription glasses under my helmet, and by moving the helmet with my hands I can dis-lodge my glasses.
Oh yea... I use an AGV dark smoke sheild. I also carry a clear if I'm going to be riding late into the evening/night.