Interesting. I wonder how much the grease reduces that. It would seem the coefficient of friction for the unpolished cage could be as high as the highly polished counter-rotating surfaces of the balls. I'm sure the difference is minuscule, especially with appropriate lubrication. I was more interested in the potential for reducing wear due to greater load distribution over a higher number of bearings. I'm over 200#, so I have to think about these things. Going from 9 balls to 11 represents an over-20% increase in bearing surface.