A few weeks ago we tested a JM1S-3TD with the and a JM1S-4TD on an earlier revision of the test stand. The efficiencies shown in the screenshot below include motor and controller losses. Based on the temperature of the motor and the temperature of the controller the majority of the losses are in the motor. I would estimate that 2-4% of the losses are in the controller and the remainder are in the motor. Thus in this torque and speed range the JM1S is running at an efficiency of 90-95%. JM1S-3TD at 50V 6500rpm and 8-10kW is a sweet spot. JM1S-4TD at 50V 5000rpm and 6-8kW seems like a sweet spot. 12-13 Nm is a happy spot for this motor. Notice the 4.4% drop in efficiency at 4400rpm going from the 34x10 to the 37x13 prop (8.9 to 17.7Nm).