Hi TJ.
A replicated solution doesn't prevent you from having to do upgrades -- because during replication, you're only syncing data, not operating system & software.
If 24x7x365 reliability is what you're chasing, then you want to migrate to an active-active scenario. If it's 'recoverability' rather than reliability, then doing once nightly copies to the remote site might work for you.
-JD.