The biggest feature I'd be interested in from these is this:

Originally Posted By: Western Digital
Noise and vibration: Typically designed for single drive applications, average desktop drives are not optimized for multi-drive systems which have higher noise and vibration levels. When these drives are added to a NAS, the additional vibration can reduce the reliability and life span of the drive.

All our 12 bay ReadyNAS units at work use the Western Digital enterprise drives which also deal with vibrations/noise better then the average desktop drive.