I might have to try this motor.
I've been using the Q128c sourced from BMS battery, as it was the only geared hubmotor around this power level that accepts a cassette. Since I live near Grin, the savings on shipping make this option competitive, tough I'll need to re-lace a wheel. Also nice is the replaceable parts on this motor. I have found the Q128 a bit fragile even when run at specified power levels and would like to run something a bit more robust.
Here are the three possibilities:
G310_fst (10.5kV) in 700c wheel with 35c tire, 48V battery
Bafang MG310 fst = 10.5 RPM/volt x 48V = 504 RPM
= 504 x 2.2 m/min (2.205 m diameter at 700c with 35c tire)
= 1108.8 m/min
= 18.48 m/s
= 66.528 kph unloaded, which suggests full power assist up to just above 55 kph.
MG310_STD in 700c wheel with 35c tire, 52V battery
Bafang MG310 STD = 8.5 RPM/volt x 52V = 442 RPM
= 442 x 2.2 m/min (2.205 m diameter at 700c with 35c tire)
= 972.4 m/min
= 16.2 m/s
= 58.3 kph unloaded, which is still quite fast, but might be better efficiency for urban riding where I average 40-45 kph on the flat with 500W motor power.
MG310_STD in 700c wheel with 35c tire, 48V battery
Bafang MG310 STD = 8.5 RPM/volt x 48V = 408 RPM
= 442 x 2.2 m/min (2.205 m diameter at 700c with 35c tire)
= 897.6 m/min
= 15 m/s
= 54 kph unloaded, which is certainly suitable for my uses. Also, 48V batteries are a bit cheaper and more readily available.
Now here's the oddity. When modeled on the motor sim with the power levels I plan on using, the slower motor is predicted to overheat more quickly at the same power levels. This difference is more pronounced when modeled with the default 20A controller. It's almost as if the two motors are reversed

Am I missing something?
2012 Kona Dew Deluxe, Q128C and 9spd cassette, S12S sinewave controller, 48V Panasonic battery