I have never heard of an auto-level ever failing. Most roll-overs are caused when the combine slides on a hill, then catches and flips over. There also have been cases of broken axels. The Gleaner rotaries are popular because they are like a Goat on hillsides. Even though they don't have leveling, they are low to the ground, have duals on the front, and rear wheel assist. With the engine over the rear wheels, they are better balanced. They will go places the machines equipped with leveling won't.