For various reason we move the mailbox, some times to fix a issue or some other reason. One big disadvantage of moving user in Exchange 2003 or Exchange 2007 is it will lose Dumpster.
Exchange 2010 Move-Mailbox does not delete dumpster when you move the mailbox. This is one of the good Interesting Features of Exchange 2010
Shameless Null Neutrality
A couple of points here: The command in Exchange 2010 is now New-MoveRequest. Yes, the dumpster is maintained, providing the source and destination mailboxes are both Exchange 2010. If the source mailbox is on a server older than 2010, the dumpster WILL NOT be moved. There are a lot of misconceptions about dumpster retention in Ex2010. I advise you to try the move with a test account first and see for yourself.