Yes, my home server is running smoothly-ish. I have a USB network card that throws out a few annoying errors on the console but a) it’s maybe once per hour, b) it’s far from serious, and c) it’s a known bug caused by the kernel so it’s nothing Nethserver can be held responsible for. 
Briefly, I would like to backup over FTP. When I get a bit more time I’ll dig into the various settings and action scripts to see if I can make that option available as it is supported by duplicity. I can already see that the three options available all involve mountable destinations, so it may be more involved than just throwing in a new option with suitable parameters.
And I’m am of course reading threads like backup-data-cloud. No sense in ignoring valuable experiences from other users. 
(Btw, I found an old USB disk with a separate powersupply(!) and used the instructions in the Backup manual page to format it with ext3. Works like a charm now.)