This is a great recommendation. I substitute other products for Poxy - not because Poxy isn't good, just that the other products I use are immediately wiped off. Poxy is a great sealant/wax.
The advantage these 3D chemicals have is their ease of use, flexibility, and effectiveness. My biggest pet peeve with any abrasive polishing liquid is dusting, because it just creates more work for me. The 3D line aslo doesn't stain trim or moldings.
If you can return the M105, M110 or D300 are better options. That being said, M105 cuts really well, and when the conditions are right (temp / humidity/ air flow / miindset / technique / prayer for the fathful / divine intervention) it actually works great
With 3D ONE I use Buff and Shine Uro-Fiber pads for correction work, and their yellow Uro-Tec for polishing / finishing. In those instances that require deeper correction I'll use 3D ACA500. In the very, very rare instance I'll use 3D AAT502 for final finishing. 3D ONE is usually sufficient for my finishing.
Griot's G9 is probably more than capable for what you're needs are. I regularly do paint corrections with an original Porter Cable 7424 polisher. I have an arsenal of Rupes polishers that I use as well, when I need more performance out of my polishers. If I can get away with the PC I prefer that tool. It's light, small, durable, reliable, and easy to use.
Regardless of what you choose, the more you work with a product, the more you get to know it. For instance, I learned that if I use too much 3D ONE it's smeary upon removal. It was a turn off at first, but after a reduction of product on the pad it's been a breeze.