I tried using a Hyperdrive Space for the same purpose. I was told that the Hyperdrive doesn't care what type os file it saves and so .WAV files should be no problem. On the strength of that assurance, I bought the device.
I had a friend back up a series of concerts on the device. It now shows that almost 20GB is in use. However, every folder is showing as empty when I connect it to a PC. A photo file I had uploaded earlier is mysteriously corrupted.
I have written to Sanho and have gotten no response from them in 10 days.
I still feel that I may have a bum unit. I should know in a few days when Sanho gets the device on its hands (I am returning it to them for them to take a look at it).
I would also like to know other people's experience in this matter.