I have the DRU-500 and have not found any problems with the media I use. Fujitsu, TDK, and Memorex all work fine. As a matter of fact, the only coasters came from Sony media. Go figure.
They all have quirks.
For data backups, the Sony works like a champ. The RecordNow DX software is really easy to use and allows you to create backup tables you can recall for redundant data dumps.