If you're worried about "proven", I'd want to see how this new toe design on the TPU-X works out, especially if I was a toe dragger. The old design doesn't seem to have worked out so well. If the new toe wears out in the matter of a year (or less), the shoes are toast, and so much for your up front savings.
Yes, the TPU-X soles are about $15 vs. the $30 for the 9s. But how often do you replace soles? For most bowlers, it isn't very often. Most bowlers get through a league season using the same sole. When you amortize the difference in cost over time, the additional outlay is minimal.
The buy decision should be more about feel, with consideration for how hard you generally are on shoes. If you like the TPU-X, and you're easy on shoe wear, maybe it's a better buy for you. If you abuse shoes, the design of the 9s suggest they'll probably last a lot longer than a pair of TPU-Xs. Time will tell.