Looking on their website they show some photos of the control box, and it does not appear to me that they have the circuitry needed to add and remove capacitors to keep the voltage balanced. -as such, they are no better or worse than any other RPC if it is properly ballanced and large enough.
why not just buy a kit off ebay and find your own motor?
there seems to be some talk about special motors, specifically low impedance rotors produce better balancing, I believe American rotary claims this. i tend to believe it, but you can just use a larger motor to compensate for any benefit.