Ask anyone I know, I use these sunglasses all the time. I am a cyclist and nordic skier and these glasses are perfect for both activities.
They are light weight, comfortable, have a great lens coverage, and the scoop ventilation works...really well. I've always had problems with glasses fogging up when skiing but the scoop vents keep that from happening.
Interchangeable lense are key for these. When racing 'cross I would switch back and depending on light conditions/weather. Clear lenses for rainy/muddy conditions and the darker lenses for sunny days.
Highly recommend these, give em a shot and you wont be disappointed.