Not a very good idea. There are issues with using BIAR as backup or for migration purposes.
BIAR file is created using the import wizard.
It depends on what you want to do. If you need to create a BIAR file as part of your backup, you select it as destination. If you need to copy content and metadata to another repository, the BIAR becomes your source.
Your BIAR contains all CMS data and files as well. However there are a few exceptions like global settings etc. You need to read the Import Wizard guide to confirm.