I've always kind wanted something akin to this, but through complacency due to lack of drive failures I have never made backups a priority. Its always on the edge of my mind though.
I think the DS212j is more my style and needs. I don't need a ton of space but I can see the need for the redundancy of at least two drives. Costs does not seem extreme, I'm kind used to shelling out a bit of cash for things as outdoor gear can be quite expensive. Probably overkill, but it would be nice to have the safety net and then not really have to think about it ever again. A small dream of mine has always been to take our fairly large catalog of dvd's and put them on the network. But mostly I don't want to lose my music and picture library.
Thoughts on reliable, and compatible drives?