We've use them for several years as our man drive, and have found them to be very smooth. Are
you driving them with CIMs? Be certain the sun gear is not too deep into the planetary gears in the 1st stage. In addition, we have not had a need to use super low, as there is not much difference in ratio between 2nd and 3rd. Possibly, if you are using a servo to shift, it may not have enough throw, and you're not fully into 3rd gear. Did you remove the clutch pins from the output shaft? Are you still using the torque ring adjustment?