But I wear glasses all the time and a Pin-Lock insert does nothing to prevent fogging on the glasses. My solution was to use a snorkel during times when fogging would be an issue.
Basically an idea, whilst I wouldn't like to have something between my teeth when hitting a pothole...
Dunno about other brands/MFGs, Shoei offers/includes a breath-deflector to be clipped on top of the chin-guard/lower edge of visor frame, works quite good IMO...
(GF misses that in her C3 lid... not even avail as accessory...)
And then there skeedo modular helmets with heated visor, integrated jet-mask, the whole shebang...
Our Exome Modular Helmet is available in 3 different variants all of which offers protection, comfort, and performance for those long rides.
www.ski-doo.com
I recall a similar system offered as motorcycle helmet over here, even featured filter inserts (ideal for those with allergies), did vanish though...