@mogoodrich, I don't see any issues with assigning and storing a UUID of the set.
It seems we missed to add retireMetadataSetMember to the service. You can still do this by calling setRetired on the member and saving it. I wanted to enforce retiring instead of deleting as it is easier to track changes that way and move metadata around between servers. It is also to make sure that if anything relied on that particular set member it is still there, but can be reported as retired.
@bharatak, there's a UI built as OWA. Please see http://int02.openmrs.org:8080/openmrs/owa/metadatamapping/index.html#/ (can be accessed from home page -> configure metadata -> manage mappings) We're very much interested in doing a proof of concept of incorporating it in Bahmni UI by overwriting UI elements like header to fit in Bahmni. It is to open a way for more OWAs to be used by Bahmni and of course Bahmni writing OWAs. Let me know if you think it is feasible.
I'm fine with doing 1.20 release in a way that doesn't interfere with other devs like @mogoodrich, who are already picking up the 1.20-SNAPSHOT. You could do the release either from a branch or a master. In the latter approach you should do revert, release, reapply within hours to prevent blocking anyone from committing to master.