Using a good jig, you can get really nice results using a compact router. Buddy of mine built one from a polymer lower, was even easier than my aluminum one. I don't trust poly for firearms though, at least not for the AR platform. The stress at the point where the buffer tube meets the lower has to be enough to crack poly.
I'd love to get my hands on the GG2. Hell, a GG1 for that matter. No moolah though. Not enough for a CNC machine, anyway. They're nice little gadgets though, if you don't mind kicking around for 3 hours to crank out one lower, perfect though it may be.