You can "calibrate" your power metrics by climbing a steep hill over 5 minutes long that has a know elevation change. Plug the numbers into a online power calculator and verify which measurement is correct. I am guessing the Kickr will be correct. Most people will have imbalance from right and left power, it will also vary with level of effort and fatigue. I have two sided Vector power meter, 4iii single sided power meter, and a Kickr. My R/L imbalance is 2% at low effort and 0% at high effort. Once calibrated they will vary less than 2% overall but the Kickr lags on high power spikes.