This is a pretty interesting subject (that probably means I am a psycho shut-in). A few things....
If the ceramic balls have less contact area with the steel, won't that add up to more load in a smaller area? A hybrid bearing might just result in the races wearing out faster. Story......the first run of AMT ACPs (Colt Automatic Pistols, for those who are not gun types) were stainless, but the AMT folks found that there was a lot of galling in the slide area. I believe they refined the materials and the fit and finally got it right in the later models. It's just an example of a case where the use of a supposed superior material required a lot more tinkering than folks expected.
With less thermal expansion of a full ceramic bearing, I'd like to hear how they install. Most of us use a hot/cold process to install bearings.... it'll be interesting to see if there are issues during assembly . I hope you'll report back, Brad, the whole ceramic bearing thing a great development. I suspect the price will come down drastically as the technology matures.