I don't know, I've been snowboarding for a long time, have been crashing for a long time, and the amount of crashes where my face (not head) was an impact zone was like 1%.
Goggles actually work to protect your face by creating a small buffer zone, so the only area you really have to worry about is your chin. I have a brim on my Bern Watts too which helps too.
All in all snowboarding is a dangerous sport and you just have to accept that no matter what measures you take you still run the risk of hurting yourself. I wear a helmet but anything else I find to be excessive.
PowderHound and TreeNinja