The sense of low pass filtering is to remove the ringing from Vsense only at that moment when Vsense equals Vref, means when the comparator is switching, at the end of exponential rise of Vsense. It's not to totally remove the ringing from the whole curve. So, 47R + 10nF should be sufficient.

Now, can you speed up the repetition rate of sync pulses a bit, while keeping the sync pulse length constant? This would still increase the motor current and give you a somewhat higher torque. Or are you satisfied with the achieved torque so far?

Kai