Hi All,
I do not know if this helps or not but let me share my experiences.
I have a 1TB Duo which is about 6 months old. The Duo is set up to be mirrored, thankfully since one of my hard drives failed. I have attempted to restructure the disk 2 or 3 times since the failure but each time it fails. During the restructure I retained all of the data on my Duo.
I have been backing up my Duo using a 500GB USB Drive. I did not realized though that the backup drive was not backing everything up. The USB drive was formatted for FAT32, my fault. So any file over 2GB did not get backed up. The reason I choose FAT 32 is so that the backup drive could be read by both my MAC and PC OSs.
I am now in the process of RMA'ing the Duo. It would be much better if Buffalo sent a replacement drive that I can install myself. It seems like a waste of money and energy to send everything back. According to the RMA they want the unit, cables, CDs everything. However before I send it back I am picking up another 500GB drive to back up everything on the Duo. I do not want to overwrite my only backup in case the second drive fails on the Duo.