I have managed to get the C# and db setup using ListMappings. However, when I try to deploy the split/merge tool to Azure cloud classic the service it states 'The requested VM tier is currently not available in East US for this subscription. Please try another tier or deploy to a different location.' We tried a few other regions with the same result. Do you know if there is a workaround or updated version? Is the split / merge service even still relevant? Has anyone got this service to run on Azure lately?
https://learn.microsoft.com/en-us/azure/azure-sql/database/elastic-scale-overview-split-and-merge
The answer to the question on whether it is still relevant, in my opinion is ... no. Split-merge is no longer relevant with the maturation of elastic pools.
Elastic pools with one data base per tenant seem the sustainable way to implement multi tenancy with legacy code. The initial plan was to add keys to each of our tables to have multiple tenants per database. Elastic pools give us the same flexibility without having to make breaking changes to our existing code.