I've seen these before, and the work only on certain conditions. I wouldn't trust them in the woods, or swamp, or snow unless they are hardpacked. Best thing for getting out in the middle of nowhere in the snow is a ski mobile.
I remember once getting out to a camp in the wintertime, they brought in a bulldozer and angled the blade to plow a road in 2 feet of snow for the trucks to get in. Took 2 hours to go 4 miles with a caravan of 4wd trucks, lead by a bulldozer. Of course the guys on the ski mobiles got there in 25 minutes ahead of us in the convoy.