PID tuning can be easy or a real pita (a lot has to do with how good the feedback is and the time to get feedback), could be 10 minutes or 10 days :)
I understand the benefit of having a smooth output driver, just makes everything easier.
"salmon skin, which is apparently due to mis-centration of the encoder relative to the motor shaft."
Maybe Howard could modify his code to see how bad this salmon skin effect is? His current graphs for the servo stepper look awesome imo.
I am guessing anyone serious about AI would be autoguiding anyways, but that may not be true for this crowd.