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.