Bandaro, the MAC is an outrunner inside the shell. The appeal of that for me is that compared to another motor that is an inrunner and has a comparable size, the outrunners magnetic flux (the magnet air-gap, where the work is applied to the rotating bits) is farther away from the shaft center, giving an outrunner more leverage, and thus more torque per the same watts applied to the stator-coils.
As far as weight, I like that the MAC has more copper mass than the GNG-V1
If you like that idea, but want extra quiet, consider getting a slow 12T, converting it to shaft-drive, and removing the planets. Make an aluminum adapter to pin the shaft to the sun-gear on the magnet-ring/bowl, and add a belt-reduction to the 17mm shaft. You can also use a hole-saw to remove 40% of the mass of the magnet-bowl, so it looks like the Bafang magnet-bowl.
edit: the un-geared 12T MAC has a Kv of approximately 30...
30-RPMs per volt,...6T is 60-Kv, and so the 8T would be around 45-Kv. Concerning cumbersome reductions, the GNG-V1 has a Kv of 67, and at 72V, it is pretty much a "no pedal" scooter with the pedal cadence being way too fast to add any pedaling. There is nothing wrong with that, but the MAC/BPM both have lower Kvs, more copper mass, and 40% greater magnetic flux leverage (due to being outrunners).
On adding a belted primary (removing the stock gears): Of course this would require cutting a significant opening in the planet-gear side of the motor casing for the belt to get out. I would recommend keeping 4 of the six side-plate screws (one in the center of the belt-path with two cut-out openings for the belt), and three screws on the front half of the sideplate (this is to add rigidity to the shaft bearing location). There may only be room for a 15mm wide belt to exit a stock-width motor case (IDK), but you could add spacers under the sideplate and use longer attachment bolts so the sideplate is moved farther out. That would make more room for a wider belt.
Its all experimental at this point, but the potential benefits are too appealing for me to stay away. Even if its a complete bust, this is a lot of fun for me. I spun the motor recently as a shaft-drive using 24V and an RC sensorless ESC. The motor seemed to spin fine in forward and also reverse.
Does anyone know if the MAC neutrally timed?
Pic of the solid STEEL magnet-bowl on the MAC:
Pic of the skeletonized STEEL magnet-bowl of the Fusin geared hub, to reduce weight:
Skeletonized aluminum stator-core on the BMC to save weight: