If you regularly use Features to deploy a site from dev to staging to production, you’ve probably come up against a problem with file fields not behaving themselves when you add them to Features. This problem is particularly bad with taxonomy terms that have an image field, which are commonly put into Features as part of the site structure rather than client-entered data.
GUFF (Generic UUID file fields) solves this problem by providing an automated system to encode managed files (eg, file fields) into .php include files that are handled through the standard Features system, and can be put into version control.
GUFF works with UUID files, and once enabled it should Just Work. Has saved us a lot of pain.