This is a bit off topic but probably reassuring to those who back up AC including Imported Items. I have been concerned because my daily backup file (.enc) was so large, approaching 25 GB. So I did a trial restore from my ".enc" file on a non-networked computer. It takes over an hour for the AC Backup Restore program to complete, and you need considerable disk space to un-zip and unencrypt the .enc file (about 3 x the size of the .enc file). But it worked flawlessly on two separate backups.
