You can also setup vlans to separate the networks. Custom firmware for your router might support this, otherwise you can find a relatively cheap switch to throw into the mix that can help you with this.
I created this account just to reply here.. First, sorry for digging up an old topic, but did this really die here? OP, what was the outcome? Did you get to try the NSA devices? I have an NSA device Id like to load a custom firmware on also. Hoping for a reply.