Channel imbalance is only noticeable if the analogue pot is set at the lower ranges from 7 o'clock to 9/10 o'clock positions. Past 10 o'clock it's not an issue anymore. While true a digital pot is superior to an analog pot across the full range, modifying the low gain to -12dB on 6SMKII makes it a non issue on sensitive iems.
Mine is only noticeable at 7 or below with my EX1000. Never been an issue and never even thought about it.