I just recently picked up an OSBE helmet and after skiing it for three days have found it to the answer to my vision challenges while skiing.
I need to wear glasses while skiing and none of the goggles, glasses, wipes, drops, cloths or anything else I tried worked for me. Not even my trusty old Bolle mountain bike racing glasses with the prescription inserts.
The OSBE flat out works and fogging problems so far have been non existent. The helmet allows a very wide view when the visor is down and tearing has not been a problem in temps down to 10 degrees F while skiing at speed. The visor seal keeps enough wind out to be effective, it is not a complete seal like a goggle provides but it is enough. Flipping the visor up and down as needed is very handy and there are no more goggles popping off my helmet and flopping around. The visor can be changed for another color in about sixty seconds once you have done it a couple of times unless you drop one of the parts.
The color selection on the company website is impressive and the colors are even more striking when seen in person.
The OSBE website sizing chart put me in the middle of the small size which really surprised me. My GIRO G9 is a large. I called the US distributor and asked if the sizing chart ran small and was told that it was true to size. So I ordered a small and although it fit, it was very tight and I did not think I could wear it even an hour without having real problems. I called the distributor and returned it for a medium without any problem. The medium was also snug (as a helmet is supposed to be if it is to protect your head), but I felt I could live with the fit and it has proven to be fine even after a full day of skiing.
Although I was worried about spending this much money on another experiment, it turned out to be a great success. Also, the OSBE US distributor offers a thirty day return policy if the helmet doesn't work out for you (check their website for the details).
I highly recommend the helmet if you have to wear glasses, YMMV.