Scott,
All I can tell you is what a local dealer told me. He said the new eHydro trannies are adaptations of Hydro trannies from the big JD ag tractors that JD has used successfully for several years. They simply 'retrofitted' (whatever that means) them for the 4000 series. He did say they ARE NOT completely new designs that JD created for the 4000 series. This relieved my fears somewhat as I hate to think of 'bugs' that'll have to be worked out of these so soon after I get mine. We'll see though. Hope this helps.
Regards,
Bob Ancar
Cambridge, NY