>I'm having trouble deciding whether I should do [some backups] on entrance or exit to the app. No single session has a lot of edits, but it is used daily. Opinions?

Would you rather wait for a backup when you start, or walk away when you're done as assume the backup is happening? Even if it only takes 3 seconds to backup 2 files or the entire hard drive, the user will complain about the wait when they start. (I complain about the lag from launch to first line of code execute= <=1.5 sec?)

Since no session has a lot of edits, you might want to create a duplicate system. ex: a "working" table, and a "storage" table. Each occurance of an INSERT or Replace on the working table has the same operation applied on the storage table. Your routine could validate that both tables are synchronized, and if not- determine which has the correct copy. This would guarantee a high level of data integrity at the expense of simplicity. (and would be a mess in code if you have many tables or several modules for manipulating each table)