I don't like it because it "clips" to the wheels, and uses the tire to drive them.
What happens if you a hidden tree stump or something like that, and it pops off the wheel?
I like the ones that "replace" the wheels, though the issue with these is the "spur of the moment" snow-wheeling.
Mattracks.
Here's a couple videos.
Heep, but if a Heep can do it, so can a Runner.....
<iframe width="420" height="315" src="https://www.youtube.com/embed/Q_yhLcnkJFM" frameborder="0" allowfullscreen></iframe>
and Ken Blocks Raptor.
<iframe width="560" height="315" src="https://www.youtube.com/embed/5aeKdmw9W50" frameborder="0" allowfullscreen></iframe>