Gary has the Black Magic motors for sale on his site at
goldenmotor.ca but they are only really suitable for external controllers.
I think it is will be a while before GM start developing vector controllers suitable for this particular motor, and an internal controller option would probably require a complete redesign of the motor in much the same way that the MPII was completely redesigned to create the MPIII.
As for roll resistance, the larger a direct drive motor is the more resistance it will have. People say the motors are easy to peddle with the motors off. I don't agree with that. Of course you can pedal home with a dead battery, but to set out on a ride thinking you will just pedal and turn the motor on later is not realistic.
I haven't tried a Black Magic motor so I can't comment on the resistance, I do know that the resistance of the Magic Pie is very noticeable above 10mph, but the Smart Pie freewheels very easily in comparison.
I would say that the only real difference I have noticed with the Smart Pie is mainly due to the increase in weight being carried as installing the motor and battery pack obviously makes the bike much heavier. I'm pretty certain that it freewheels downhill at the same speed it did before the Smart Pie was fitted.
When you constantly ride with motor assistance you soon forget how difficult is is to pedal a conventional bike as you soon become dependant upon increasing the throttle to get you up the hills instead of increasing your leg power.
I used to pedal everywhere before I was sixteen, then I stopped using my pushbike and took to a moped instead.
About a week later I couldn't get the moped to start, so I had to ride my pushbike 3 miles into town to buy a replacement spark plug. I couldn't believe how slow it was in comparison with the moped and especially how hard it was having to pedal to get anywhere.
Alan