Glasses performed fairly well under heavy snow:
Descended (and then climbed back) alpe D’huez as weather too poor to ski.
Glasses got quite a bit of snow on the outside, but that doesn’t affect the display.
However, in a long and steep descent, with humidity at 100%, and snow / rain, things tend to fog up. Vision remained good, but the optics for HUD fogged and so I wasn’t able to see much stats towards the end of the descent. I took them off and rode a few hundred meters without them, in the hope to de fog, and that did the trick. Not at 100% as the display wasn’t as clear, but could still read my power/cadence/HR/speed very well, and leave the climbing page on the Garmin (which was hardly readable due to snow/rain).
One thing I really like is that how the display doesn’t distract from the road. However, when you look at the stats, you can still see the road very well (unlike when looking at a bike computer).
I was out for only 2h, so couldn’t test battery performance (which has been very good) in sub-zero temperature.
I’m very happy with the glasses, and would definitely buy new ones immediately if I broke or lost them.