AADConnect Server Array
If you start doing password sync and password self service reset, etc. it makes AADConnect a pretty critical service. It would be great if the AADConnect setup wizard and the service in general supported an array deployment such that it could assign primary and staging roles and be aware of other servers in the array. Having the ability to control failover to an array member... etc. Support for each server using SQL Express, individual SQL Server instances or a centralized SQL instance shared by the array. When you have a custom configuration, maintaining AADConnect instances can be a real painful experience with how isolated and manual the setup of each is...
We are currently planning for a high availability solution for Azure AD Connect but cannot share any timelines at this moment.