If you want a diamond sharpener nothing I'm aware of can even approach the quality of Japanese Atoma plates. They're very expensive but you can get a small slice made for Edge Pro use for a lot less. These 1" x 6" strips are mounted to EP blanks but are also perfect for portable use freehand.
I acknowledge your expertise in sharp-making, and the resources expended to obtain the best sharpening equipment. I ask this based upon ignorance only, and ask your indulgence: Other than expense,cachet, and user skill, is there any difference between a 1000 grit japanese water stone and a 1000 grit sheet of emery paper contact-cemented to a sheet of glass? It would seem to me that the issues are the relative hardness of steel and abrasive, and the flatness of the abrasive surface. Thank you-Mike