I had an rtv500 for 3 years, it was the best for ice fishing unless there was over 7 inches of snow. Even with 4 wheel drive and the differential lock on, that thing got stuck all the time. Great for everything else, but horrible in the snow. Maybe the 500 is underpowered, not sure....... but that is why I sold it. BTW I was comfortable with anything over 8 inches of ice. Hope you have better luck.
Jimmy