So here are my thoughts on the G9, a machine that I don`t even have!!!
I used several different polishers on a car this past Saturday. I did a test spot with the GG6 with a Megs 3" MF Cut Disc on a curvy part. Went well, finished off quite decently.
Followed up with the G15 with 5" Megs MF Cut disc on a larger, flatter section. Didn`t finish out as nice.
Swapped to the Flex 3401 with the same pad combo, and it finished off better than G15
Observations: The GG6 felt "heavy" to me. Also, felt like it vibrated harsher than I remember. Following that up with the G15, that machine actually felt a bit lighter, a bit quieter, and quite a bit smoother than the GG6. What made me STOP using the G15, was that the cutting stage with the larger orbit didn`t finish out as well as with the other two machines with smaller orbits.
Right then, i decided I really do want the new G9.

What made me NOT go out and buy it? The fact that the particular use for the GG6 at that moment, I was using it with a 3" pad! Can`t do that with the new G9. Oh well.