The general goal is calculate or tune a FeedForward gain so that the sensor velocity is near the target velocity. P (and potentially D/I) are then tuned to respond when the velocity error is nonzero. This allows for an aggressive closed-loop response with less overshoot caused by large changes in target velocity (let F do the heavy lifting).
To make this clearer we provide an velocity closed-loop walkthough in our documentation and examples on our site/GitHub.
Section 12.4 (Talon SRX Software reference manual)
http://www.ctr-electronics.com/talon...ical_resources