In essence, what can be backed up is pretty much automatic ... at least not for the CURRENT unit being called the GO 520 (see dhn's manual page).
The good news is that you can recover firmware levels (pretty hard to brick these new ones) and your maps are always 'on account' at TomTom if anything ever happens to those.
However, there was another being sold under that name back in 2007. THAT one can be backed up in its entirety, and probably should be.
So my answer depends upon which one you have. Am guessing you have a more recent model, but...