Yeah, instead of spending $10 on diodes, go spend over $100 on a speedo that still needs a diode for under 10 turn motors.
From Tekins website
" G10-Pro Servo glitches:
Today’s low turn motors are pushing the limits of the ESC's ability to deal with back emf from the motor. Below a 10 turn motor you may need a Schotky diode across the motor."