I have been thinking a lot about your post Gull Wing. As I have said before, I feel the "smoothness" of a CRK is most affected by the gliding of the ceramic ball (in the case of the 21, a very small ceramic detent ball, and in the case of the Inkosi/Umnumzaan, a large ceramic ball that is also the lock face) across the surface of the knife. I think in most cases a "gritty" knife has a dirty detent track, and the condition of the washers or pivot is not really the culprit. When people break down their "gritty" knives to polish washers and lube pivots, they incidentally clean the detent track as well, so do not necessarily diagnose the cause of the grittiness, or what they really did to fix it.
I agree the Inkosi (in my case a 25) is the smoothest CRK. I think the reason is the diameter of the detent ball is larger, so it glides over the stonewash on the blade, or the track that gets worn into it, more easily. Just as a larger wheel will make it easier for a bicycle or car to roll over rough terrain, the larger ball is less affected by imperfections, scratches, sticky residue, and grit on the detent track as you open and close the knife.
I am well aware the ball does not roll, but the 'angle of attack' is lessened, and the size of the contact patch is enlarged, providing the same benefits to the knife feeling smooth as it would to the wheels on a vehicle. The ball does not get hung up as easily, nor does it fall as far into any scratches on the track, hence it being so smooth.
Furthermore, the larger detent ball will move out of its nesting hole easier, requiring less effort to get moving as well.
In short.......I agree!