I can't get used to all that glass weight on the bridge of my nose, the Titaniums are light as a feather.
I scratched up the first pair but got smart after that and now make them last for several years without scratching. Just use a neck loop, cinch it up when leaning on the gunwhale to land a fish and you're good for years with plastic. Some companies will replace the lenses for short $ if you are not the careful type, or go with glass.
Polycarb lenses are safer for the eyes since much of the injury occurs from the glass itself vs. the object shattering it. "Plastic" will not add to the damage in fact it's the same material used for shop goggles. Skiers will not use glass lenses, shooters, etc.
IFFF Certified THCI @ 2005
Capeflyfisher Guide Service
Island Hopper, Guitarist, Incurable Dreamer
and Founder, Worldwide Flyfishing Forum