Hard to find the NSS 7 or 9 used. I searched for a while.
I bought a GO7 and a GO9, tried to GO7 and ended up ordering a NSS7 Evo3. I got the GOs at a pretty good price and wanted to see first hand the size difference, plus use the touch screen. Ultimately, I wanted to buttons and actually the higher resolution on the Evo3 - roughly 50% better resolution and I bought the C-Map Reveal to have satellite overlay. It just wasn't as sharp on the GO7.
I may be posting the GO9 soon, or I may just keep it and trade out my Raymarine Dragonfly on my center console.