Ok, so here we go, I did some tests:
Sony USB2 stick on USB2:
Kingston USB3 stick on USB2:
Kingston USB3 stick on USB3:
SATA II disk on USB2:
Same SATA II disk on USB3:
You can clearly see that there is a difference, meaning an increase of speed, when using USB3.
However I also tested with the IO Level Up set to USB3, but there was no difference as to leave it disabled.