Our organisation is doing a migration of Exchange 2010 to a different Exchange infrastructure, and all the mailboxes will be migrated across. Our users will stay on the same AD domain, but the new Exchange is in a separate, trusted resource forest.

Currently we have two BB servers: a BES 4.1.6 server (which has given me funny DB errors when trying to upgrade it, which is why it's still on 4.1.6), with around 80 users, and a BESX 5.0.3 server with around 250 users. They are in different BlackBerry domains.

What approach can I take to minimise the impact to our users as we migrate? I really don't want to have to factory reset each device manually to move over (as we have to do moving from the BES server to the BESX server). I can easily set up another BESX server, if needed.

Suggestions?