I rsync my profile between multiple machines and I frequently get the error that my profile was created by a newer version of Firefox. It would be great to have a button to Upgrade Firefox right there so that after restarting I can just continue to use my existing profile.
Currently I have to: Create a new profile, Update Firefox, restart, open about:profiles, reselect my default profile, quit and restart, then go to my Profiles folder and remove the new profile (which I often skip -- I have dozens of these one-off profiles now that don't appear in my About Profiles).