Unlocked frame rate increases response time of the controls....
Locked = Better image (no screen tearing) / Worst controller response time
Unlocked = Worst image (screen tearing) / Better response time
It is a trade in/out... advantages and disadvantages.
I prefer always unlocked even on PC.
Locked= Constant controller response time.
Unlocked= Variable controller response time that can be greater, same or less than locked depending on moment to moment framerate variation.