This happened to my brothers blade the other week. A large stone chucked up from a truck's tyre, no amount of Venture Shield is going to prevent this. I guess he's lucky it didn't hit him.
I It's a good question and one I've been asking myself. The fairing plastic is a lot more brittle, but I would be keen to hear other people's opinions/experiences on this question. It must have been quite an impact to do the damage it did.
Ouch! Done maybe 300,000 miles on a bike and had a stone hit me for the first time earlier this year. Right on the pinky! Was enough to draw blood. Freaked me out like something else. Felt like the bike had just given me a massive electric shock.