@Barin I have yet to encounter a real need for the derivative term in VEX.
While I usually agree that PI is suited for most applications, I'd say VEX is unusual in that PD is better. PD controller has been very useful in for VEX robots in my expierence.
The I gain although increasing accuracy in long term, is unnecessary for most applications on 393 motors and often causes more trouble than its worth. E.g., for turns using a gyroscope, I can cause signifigant oscillations that result in considerable drift in the readout and inaccurate target. It also takes a long time to hit the setpoint which is not a luxury one has in a 15 sec auton.
On the other hand, PD control allows for a snappy response time by dialing up P but preventing overshot and still maintaing accuracy with the appropriate D. Its especially useful for quick turns and lifts.