Funny how the Zenn cartridge keeps creeping into this discussion 😉
As for the Sato Musen Zen, my guess is that this was indeed built by Victor, similar or even identical to Kanno’s original design. While the body looks more like the MC-L10, the construction of the coils is as the L1000 (not etched) and the specs are also identical. I don’t know the facts on the Sato Musen brand, but most likely it was a small Japanese operation specialized in audio related products. Apparently they were in the position to request from Victor/Kanno-San a special version with a diamond cantilever, which was never available from Victor.
I have both the MC-L1000 and Sato Musen Zen Diamond and they share the same sonic profile. Both are capable of producing huge dynamic swings that make the soundstage balloon in all directions, seemingly without any limitations. The Zen with diamond cantilever is if anything even more explosive than MC-L1000 with aluminum cantilever. But it also sounds slightly warmer in the midrange, perhaps due to the different body material.
The only other cartridge I know that can manage this sort of dynamics is the original Ikeda 9. This cantileverless design also has the coils directly above the stylus. Reports from other users suggest that the Decca and the Neumann DST, also variations on this ’direct couple’ theme, have the same characteristics. Obviously no coincidence!