Being a Newbie to the "NAS World" this is all very useful Info to me. When chatting to the guy in my local Computer shop he did advise on a Four Bay NAS(...and not because he just want to sell me one) His view was in the future, I may want to expand and with a four bay no probs.,More Back up options etc...

In my mind this was a bit OTT. why not just have 2 bay and 3 HD external drives (In different locations)..? I always considered 4/5/6 bay Drives were more for Surveillance purposes , Or where somethings filmed on a loop... But Thinking again a Four Bay one may be a better long term solution....
...There again Iam only having FLAC. Music Files on there NO video, Film etc...