Channel style bearing system?
I was reading up on how IKBS works and I had a thought. What if you drilled the bearing race into the tang instead of the 4 handle pieces? It would basically be the same as IKBS but inverted.
Assembly would be more difficult than IKBS because 2 sets of bearings would have to get placed at once and there would probably have to be some kind of guide in place to keep everything together until a pivot screw could be inserted.