Ive got a Netgear Duo with 1TB drives. Works well, and we have 3 at work as well for various departmental use.
The Duo's have 2 drive and rather than proper RAID have the drives mirrored.
Id have another one - they are great pieces of kit.
The Duo's can be a bit noisy if they are in the living room (Mine is behind the telly) and the main power led is very bright in a dark room.