Mine broke after a high RPM shift to 2nd on a public road. Based on my experience, I believe that this provides just about as much shock to the differential as a 6000 RPM clutch drop at a red light. I have over 36000 miles on the car and the failure was due to fatigue failure of the pinion teeth. I believe that it is possible to drive the car in a spirited fashon, without abuse, and still destroy the differential. Also, my factory replacement is much smoother and much lower friction when performing the differential test of:
1. Putting the car in gear while turned off.
2. Jacking the rear off of the ground.
3. Rotating one tire and checking that the other tire rotates in the opposite direction.