In our support team I allways tell users to dl gedcom and all files in /media.
I think it is a little more complex than that. I see two different reasons for a backup:
To protect your family history data. In this case your advice is absolutely correct. The Dropbox suggestion is aimed at making this easier.
To protect your website completely. In this case a backup of your GEDCOM file is not needed. It is far more important to backup your database, as that stores everything, including your family history data, all settings, user information, etc. But still a backup of media is required.
In both cases a backup of the kiwitrees software is not necessary as that is easily obtained as a fresh download.