Some great points, headloss!
Just to respond, I didn't mention that I wrote the company before using it to get their thoughts. Even though I tried to thoroughly explain the application and the forces/speeds involved, I have little confidence the person I emailed understood bicycles but he gave it his blessing. No worries.

Wrt to your concerns about sliding v. rolling, I'd offer that rolling involves some sliding on a microscopic level. Sliding is sliding, non? I also think the ceramic balls are harder than their races so the races would suffer more from sliding friction. But that's just a theory also. But certainly not something that occurred to me, thanks!

I found these press-fit, BB90 cartridges were very easy to open and completely degrease first (yes, very important). The seals are just plastic snap-ins with a metal reinforcing ring. Be careful not to bend too much and they pop out easily with an Exacto.