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.
I learned this the semi hard way because I discovered that my backups in one office were not "readable." The solution, as Indy stated, was to go into SQL Management Studio and do a custom backup. I never, nor did AC, figure out WHY it would create an unreadable backup (which was supposedly checked for errors) but that was the case. It did not include the import items, which I would later move separately.
Ultimately I created a "clean" backup and moved the database. It changed a one day adventure into a one week adventure. I learned a lot about Management Studio and the database, but.....
I think I'm feeling the need to do a backkup/restore of the database this week, just to be sure....... (I haven't done that in about a month.)