If anyone wants an actual comparison for an individual player who played both USHL and CHL you can look at Sam Gagner.
As a 16 year old in the USHL he put up 0.82 PPG
As a 17 year old in the CHL he put up 2.23 PPG
http://eliteprospects.com/player.php?player=10425
USHL and CHL are very comparable leagues. Playing a year in the USHL is literally the same thing as going and playing in the CHL.
Another example is Tinordi with the London Knights, be went from being a top dman in the USHL to a top Dman in the CHL.
This kid is going to play a year in the USHL and then probably two at Providence and then make the jump to pro.