We are looking to migrate AAD Connect from an old DC to a new 2019 DC. Our AAD Connect DB is currently on an external 2017 SQL server. The original AAD install is only 1 year old, but the old host server is much older and must be retired. I know that we can't be the only organization to have this type of scenario come up, but there is surprisingly little information what the best practices are.
What are best practices for migrating in this environment/scenario?
With a smaller organization, should we go with a new Express DB, or stay full SQL on a SQL server shared with other DBs?
If we migrate to an SQL Express DB, can we later move that DB to a dedicated SQL server?
Or is there a way to connect the new install to the existing DB without having to recreate it?