Actually, they've broken three ways.
With two of them, At some point in time they couldn't take the amount of switch falls I was taking, learning 540's. They would pop out and then the speed would rip the brake foreward. That happened enough to kill the brakes.
Second, when I broke my Femur, i landed on my side and my top ski/boot landed right on top of the bottom binding that was still on my foot. The force of my two legs hitting each other ripped the binding clear off the track. (This would have happened to any binding, i'm sure)
and third, I'm not sure what happened. But there is a lot of shattered plastic, and it's ripped out of the track. A different way.