Thank you @chase.freeman, @Gerald_Thomas and @bobj for your input. In my opinion this document should be used as a guide on how to decide which MDM to use so every experience here is really welcome.
Hopefully we will be able to update the document with other MDM solutions and, it time allows, develop a PoC of a small project with several devices (my tests were mainly 3-4 devices) in a self-hosted solution. I think this would be the deal breaker.
In the meanwhile we keep working on making the Android App and its Settings Web App (NEW! DHIS2 Android Settings Web App version 1.0 is released) as helpful as possible for projects that face issues due to the lack of an MDM.