3 x Seagate 1.5TB in RAID5 - used for back-ups 2 x WD 500GB in RAID0 - used for streaming music.
I previously had 5 drives (5 x 500GB) in a RAID5 but this resulted in a 1 to 2 second delay in responding to inputs on my Squeezebox Duet controller and music being streamed; this became irritating after a while. Streaming from the RAID0 has eliminated this delay completely; response is instantaneous. The music on the RAID0 is a copy so nothing will be lost when a drive fails (and it most certainly will!)
Have 5X Seagate Barracuda, ES 24x7, 250GB, 16MB, ST3250620NS running RAID 5 (4 with one hotspare) atm. I'm reading up on RAID 6 and may change to it later after I have checked out all the options and know hows it all works. what happens if a HDD in your main N5200 fails? I suppose you have to replace it and the restore from your backup N5200.