Thanks for the feedback guys, it has been helpful. So I finally decided on the 1512+ since it is way more than I need now by itself and when I need to expand in 2 years, I can add a 5 bay expansion unit. I'm definitely going to take my time and make sure I set everything up right. I bought a new gigabit switch that is compliant with the link aggregation capability of the NAS and will switch out all Ethernet cables to and from the switch with Cat6. Also bought a dedicated UPS for the unit. Should be plenty fast enough as my main concern is reliability and constancy of data access. Currently have 2 WD red 3Tb HDDs and have just ordered 4 more. 15 Tb should be a good start.
Oh, and the 2 HDDs came from Newegg and each drive was bubble wrapped, put in its own box and then the two boxes were packed in a larger shipping box. Looked good but I have not tested them yet. Anyone have a MAC or Windows counterpart to badblocks? Not going to mess with Linux.