Uploading a copy of the IIs everyday is not practical. Some people have II that are 30GB in size which is simply ridiculous to upload on a daily basis. What you need is incremental backup for the Imported Items. You can achieve that using a separate offsite backup program.
Imo, AC's offsite backup is a bit over priced for a simple file backup that only backs up those .enc files. When there are other services that will backup all of your files for like $50. I use iBackup personally because I backup numerous things: SQL, Exchange, SharePoint, Documents, and AC. iBackup has add-on/modules for these. For 200GB, it's $200. On the pricey side, but still cheaper than AC's solution for a lot more features. There are other technical reasons I like them as well. But for most people, Carbonite/CrashPlan/Mozy will suffice, especially if you only do file backups.
I was using Carbonite before, but they started throttling me after I reached a certain amount. A service that keeps me a month behind with backups is not one I want to use.