Hey Dean,
I haven't spoken to Herr Konrath, (that I know of..) but I have asked Kontronik product support about running faster than 25,000 rpm. They say that it can be done, and the 25,000 limit is conservative.
In addition, we are adding two extra bearings, a front bearing to take the axial loads, and a rear bearing for rear support, and to support any fore/aft bending moments. These two bearings will remove a lot of the load from the existing bearings. Also, the existing bearings are sized to support radial loads from belts, gears, and pulleys, which don't exist in this application.
So, if you assume that the original bearings were sized for radial loads and bending moments from belts, gear and pulleys at a max rpm of 25,000 rpm, The calculated life without these loads, is actually considerably more, even at 35,000 rpm plus. Also, the bearing sizes used in the Drive are good for 35,000 rpm to 45,000 rpm plus, so I think we're good.
Brenner ...