I just don't think that this thing will really work "as advertised".
It may be possible to tune it up to 24K for very small angle... BUT, then what will happen when you put some content in with large angles? Experience tells me that it will massively overshoot and possibly (probably) break a torsion rod.
Then, it may be possible to tune this amp up to work at larger angles (which is what the G-120 is supposed to do), but then small signal response will be crap (like 15K or below, as he shows in some of his other pictures).
This amp has no "angle intelligence", so it can either be tuned up for small signals, or large signals, but not both at the same time. This amp will also "sing", depending on the mirror/mount you put on it.
So, in the end, I think (gulp) Chinese scanners and amps would work better than G-120s and this amp, and probably be less expensive too.
But in any event, if someone has some money burning a hole in their pocket, sure, go ahead and get it. It never hurts to experiment and sometimes that's the best way you learn.
Best regards,
William Benner