Originally Posted by JT_2eighty
Tough is bit stiffer which I have found it to have better control than Classic, with less power too. Classic probably has better feel and power, with Tough having a crisper, 'sharper' feel to it (maybe a touch less pocketing than Classic). I seem to have better durability with Tough as well, and like the way it pairs with a poly cross, to me it blends better with poly than Classic, as it also notches less quickly than Classic. For those who find the notching aids the spin (gut oils seeping out and all that), I haven't noticed much difference in spin between the two. But I hit a flatter ball. Spin for me (i.e. kick serving) comes easier when I drop to the 17 gauge from the 16L. And Tough 17 is the most durable 17g gut I've used.
You might also try KLIP Legend Tour 17g.
Highest grade natural gut with tremendous playability. Legend Tour offers 2 coatings providing a livelier feel with more durability. Very responsive string with the uniformly smooth feel of natural gut. 100% Australian. Comes in a non-traditional black color.
It almost feels like gut coated with poly. Very durable. Very crisp feeling gut. Well priced at about $25.