In my case this was unnecessary and the update to Developer Edition preserved everything. Might have something to do with the fact that I already make use of multiple profiles.
EDIT: Wait! The default profile was used when clicking "Restart" from within the updater, but when closing and reopening the browser manually it did indeed start up with a new profile.
EDIT: Wait! The default profile was used when clicking "Restart" from within the updater, but when closing and reopening the browser manually it did indeed start up with a new profile.