The flex difference between the Lithium and Probuild is very minute. The Probuild Is right at 1/4 lb lighter. The 15 off skier is probably not going to see a lot of difference in performance, maybe a bit more acceleration. Turning characteristics are very, very similar. The PMI core of the Probuild lends a slightly damper feel to wake crossings and the ski is going to be a bit faster off the ball as well which will definitely be a plus for the 32 off skier. That being said, there is nothing inherent in the construction and performance of the Probuild that will hold back the 15 off skier. The Lithium has been a great ski and would be a good way to save some money but as someone once said " If you're going to New York, why would you want to get off in Chicago?" Just sayin'.