Talk about F'd up coding, after about nine hundred license combos it was apparently too much work at MS for them to call the same class methods and allow the damn KMS PRO key to force the upgrade and lock it to ONLY accepting the public NON-KMS PRO key. You would think supporting corp customers, since I just friggin managed to literally (I recorded it) set my KMS host and activate HOME(CORE) against my own KMS server, you would then think I'm on the KMS path, so logic would then dictate to upgrade my KMS activated HOME/CORE to KMS PRO using the KMS PRO key, right? LOL, nope go find that retail PRO key - that works.....then go back to the KMS path, LOL. Yep, this ace-crack activation was well thought out and mind you thank god this is the new IMPROVED 1511 TH2 build.....
Yep, MS lies like a mo-fo, this can be done. You just need to switch keys about a hundred times and time your KMS info setting appropriately or steps can fail but it can be done. In-place all the way from HOME to ENT KMS activated with a 2 sec rest stop reboot at KMS PRO just to enjoy the view. This just screams for needing automation this might be a fun project to make a tool that automates it all. Have to revert my snapshots do bit more testing though to verify theory.
There is no direct edition change path from Home to Enterprise. There is one for Home -> Pro though. Also Pro -> Enterprise. And Home -> Education. You can look it up in %systemroot%\servicing\Editions\EditionMatrix.xml, or run dism /get-targeteditions. I never claimed dism would work in your case, because I am aware it only works for generalized images offline. And for that purpose, I know that it works without issue.
I want to thank @100 and others for their input and help! So, I have run multiple tests taking an OEM entitlement activated HOME to KMS Enterprise with no data loss and the latest 14295 build. I did capture some video and wound up losing a couple but will still try to get them posted soon. I did determine that there is a specific order to the things that need to occur specific to going from non-KMS to KMS and even though MS says that path is not supported that with one extra edition in between it absolutely is possible and I am typing on my ENT KMS activated build 14295 right now with all my apps and data totally in tact all without running any setup/media. So, my intent now is to begin the creation of a single-click tool that one could run on a hardware entitlement activated HOME and without any further interaction, log in with a fully KMS activated copy of Enterprise. I would think this has to be the #1 scenario of upgrade paths here for all the folks that have newly purchased laptops or desktops and then <ahem> want, for education purposes, to ditch HOME and quickly, safely, quietly upgrade to ENT for those missing features all while testing against a local KMS server (also for educational purposes) and not having to worry about reinstalling apps or data loss. Once I start testing some prototype code, I assume it is best practice to start a thread under the MDL tools section so I will do that to track progress and I will of course appreciate community assistance in testing as I polish it.
You can in place upgrade the home to any desktop version and viceversa, w/o any problem. Just change the edition id inside the registry before starting the upgrade