We ran Kuchar bars with our factory concaves in a 9750 and were happy with the way they worked. We installed his rotor this year and he was calling us once or twice a week during harvest to see how things were going and see if the combine was working good. I've never had anyone from Deere do such a thing. I was impressed that he was checking to see how his products were performing.
The large wire concaves seem to work noticeably better this year due to all the wet conditions and hard thrashing. Round bars only work good in dry conditions. The lack of sharp edges causes a loss in performance.
we had his bars and concaves in our 9560. did an excellent job in corn and beans. very clean sample, almost zero cob tips, and no damage to the grain. in wheat, i think his bars are better, but i like the deere small wire concave. proly not quite as much capacity as the kuchar, but you can get a little cleaner sample. all in all, well worth the money