Symantec Cloud Archive migration

Hi,

We plan to use Symantec Cloud for mail archive. We also plan to migrate form exchange 2003 to 2010. Would it be better to archive mail onto the symantec cloud beofre migrating to 2010 as this will reduce local migratuion time? Will moving mailboxes onto 2010 confuse symantec or will this be relativly seemless?

Thanks