One thing I have noticed is that when I do a full backup of the system using the backup and restore module I cannot do an actual restore. However, if I set the backup to only do the configs and CDRs it will restore just fine and even restore on another Ubuntu based PIAF PBX. I then tried adding in the system audio and voice mail options and it worked as well.
There were a few settings that didn't restore in either scenario like voice mail is disabled on all extensions, you have to manually enable and reconfigure each extension. I also change the from string and email body message in voice mail admin, those settings didn't survive either and I had to manually copy them to the new box.
Using incredible backup I am able to do a full restore as long as its on the same platform. For example, I was able to restore a backup from one DO droplet to another, but I was not able to restore to my Foxconn box. It says that it ran, but nothing was there.