Most of the time these numbers are just made by smashing the head on the numeric keyboard , eventually the performance on the track must convince you if you want it. And face it, 300rpm on 45000rpm is just 0.66% Wow, what a difference! Someone shoud use a dyno, test it with a ceramic bearing and then replace it with a steel one, I can tell you that the dyno would not tell a difference.

Beside that, there are people who do not trust NR ceramic bearings and use steel when replacing them. They do not feel a difference.