I've seen worn bearings at less than 30000 kms , and other OEM still OK at 200000 kms...
Curioulsy, most (all, in fact!) of early paralevers on R100GS, K1, K1100LT, R100R, R1100GS I have or had were equipped with long lasting bearing whereas R1150 bearings were all dead young. Quality issues of post Y2K BMW? Possible. Probable. Parts or mounting procedure...
Anyway, it's right that they don't rotate through enough degrees to divide the wear on all the space between rollers location; that's why they wear so quickly. But even if it may seem counter-intuitive, I think that an agressive riding on bumpy roads will make the bearing work at a wide angle, whereas a gentle riding on flat tar will concentrate the wear at the same spot.
IMHO, bushings is a serious alternative to be considered...