This might be a bit late, or mentioned elsewhere, but it would be nice if this:

Individual access rights, extend the access right lists to include all items in the list, so that access can be set on document level, the above group level with fallback to the module access definitions. This access will work as a refinement and not overrule any module or page rights.

included View access restrictions where only those authorized to download a document wold be able to view it.  I've looked all over for this functionality and I can't seem to find it in any download/documents module.

Cheers
Dave