As stated, about the Kaneta design for the SP10 MkII, 'there are Variants'. It seems to me to be quite clear where the Butt Stops when investigating the Kaneta Design.
The Jury can decide if the Kaneta Design is to limited to the MkII only and any variants seen are not sharing the designs concept.
Dr Kaneta is also one who is responsible for other pioneering uses of modern concepts in Electronics. He has produced designs around the Korg Nutube of which I am a advocate, I have heard this component as a key component used in Pre-Amp's and a Phonostage and am having a device produced at present utilising the Korg Nutube in a circuit that is a Balanced Design.
Peter Reinders who has evolved the PTP Design, has been vocal in their acceptance of seeing variances to his designs produced by others. He only requests that commercial ventures are not put in place utilising them.