3 Server OpenFire Cluster with Remote Cloud SQL?

If the 3 OpenFire servers are using the cluster plugin and are located on the same LAN, is it acceptable to use Amazon Cloud or Windows Azure hosted Microsoft SQL database?

The only things my OpenFire servers will be doing is process logins, messages, and presence. Nothing else. It does not store bounced messages either.

Is anyone out there doing this?

Next Question:

Similar to the above question but instead of using a Cloud based SQL provider, if I were to have my own SQL server, let’s say in a different geographical location, with plenty of bandwidth and is not a shared server/resources like the ones above are, would this be acceptable?

Or is the answer as simple as all servers, including SQL must be on the same LAN?

Thank you!