The Rokon I've had a couple in WI winters in deep snow. They are slow and it's a job to brake trail. Sure they will crawl over or through the snow to a point. 2 feet of heavy wet snow your SOL. Lite fluffy snow it will plow right through. Biggest problem with the Rokon is 5 horsepower just isn't enough, period.
I have had a Snow Hawk which is sort of like a Timber sled. They are awesome for braking trail in virgin snow. Nearly impossible to ride on a hard packed trail or road. Front ski will pull and take whatever track it wants. Throwing the machine all over the place. Maybe things have gotten better with the Timber bike.