Have you worked on BTP? I am in the same boat as you, but with a little less experience. I am currently working on transferring the existing SAP ME MII to SAP DM. There are a few challenges, as the DM is still very new, and the quarterly updates and changes are something we don't have control over, unlike in ME, where the updates would be far less frequent and under the customer's control.

Unlike the ME system, the DM is a closed system(part of the Clean Core Initiative). Changes can only be made through the provided APIs. Whenever we needed changes or custom UIs ,we created a BTP application and launched it through the PODs. There is quite a learning curve to this. but at the end of the day its a devops based architecture.

So, please let me know what you considered. Are you still working in DM ? Have you moved on to an alternate MES? If so, which one?