I'm not quite as sold on ceramic bearings with all ceramic balls. I would rather see a bearing with a combination of steel and ceramic balls. With ceramic balls they may have a tendency due to there light weight to "skid" on the ball races instead of rotate. This might be due to lot's of fuel and oil in the races. The skidding effect at high rpm's could generate a lot of heat, and the friction could compromise the ball by the wear on the ball races. It's usually the ball races that become over heated and damaged first. That resulting damage with tight tolerances can cause the ball fracture. The steel balls would have a tendency to roll more on the races and help reduce the skidding effect for the ceramic balls by reducing lubricant in the races. I don't know... just my thoughts.