egarding backups I disagree. Files related to database must be consistent to the database itself, so backup must be done saving both database and images.
I'd suggest you consider that such binary data be defined as immutable. Then the only problem you have to worry about is existence - versioning consistency goes away. You only need focus on the versioning of associations - which remains in the database and is very lightweight. It is then a separate matter to ensure that all documents you require are accessible given the identifying information stored in the database and linked to the primary records via those versioned associations.