It would be very useful for people using vesc for ebikes to be able to limit the RPM of a motor with reference to another motor's erpm. I've added a direct drive rear hub motor to a mid drive ebike and connected the vesc via canbus but, in higher gears the direct drive motor is being overspun and acting like a brake. I've also gotten overvoltage errors from the back emf I think. Being able to limit the Mid drives rpm when the hub motor is near it's maximum rpm would allow me to use the whole rpm range in low gears like 1 and 2 with out overspinning the hub motor in gears 6 and 7. Potentially this feature could be useful in other aplications as well.