Should you backup data such as linked files before updating from 7.0 to 7.1?

I have a moderately-large site with a substantial number of linked PDFs  via the link editor as well as a reasonable number of photos in galleries.  Maybe 300 pdfs scattered across 30 pages.

If I update to 7.1 via the the automated tool, do I need to worry about doing an extensive backup of these files, plus record/document where they're linked, etc, first?

I suppose I'm a little trepidatious, since just making a duplicate of the site won't backup files from the link editor, but, manually backing up on that scale will take a fair few hours?