When the snow gets too deep around here I will be considering them. I have never operated a track equipped atv but from what I've seen and have heard...
They work really well in deep snow. They are kind of a waste of time in the mud.... although I want to try them. You want the front tracks to be upsloped in the front to climb onto things and stay on top of snow. Ya, they cost you power and speed, but by the time you need them your tire buddies aren't following you anyways, so they can't keep up. Basically you will give up some things about your quad--speed and stuff in exchange for lower ground pressure.