92's vs. 93's ... would the choice differ if your using oil or graphite? Does the wheel type (such as Dynasty BASX, Rage, etc.) have any affect on the axle size choice?
You'll have to search the archives for it, but I recall a post in which QT mentioned sometimes having to use 91s to get the best speed from his wheels. I think it is all about finding the best interface for your given bores.