We use SQL 2008 Express to customers sites. We need to maintain a backup to our portal. We first take a full backup from each customer site and then restore it to our portal. Then, on a regular basis, we need to restore to our portal only the changes made to customers dbs. So, we need to take the changes made after full backup or after the last restore and 'play' them to our portal db. The customers do not have internet connections, they run on Vessels, so the backup file should be as small as possible. Differential file is not small.
Are there any other options ?