So there's a great feature in Dropbox desktop that allows you to see graphically what is taking up all of the space on your hard drive, and very quickly change certain/all dropbox content to online only to free up space.
However, it turns out that if you use Dropbox Backup, that manage feature is disabled. I don't fully understand why, as using backup as I see it, makes my desktop and documents live in my Dropbox folder set, and can be used as such, with making my own files online to save space.
I appreciate that maybe the Manage Space function may not be able to work against my desktop/documents backup, but I would still expect to be able to manage my main Dropbox Team folder content to release any old offline files easily.