My oldest WTB is from a 2014 REI brand bike, and I acquired one or two more since then. None have frayed, cracked or torn. My fiancee prefers hers to the ISM .To be clear, these are not leather saddles; just black or dark grey (what they used to call) Naugahyde vinyl. The ISM saddles are 3-4 years old, and are holding up great.

Oh, and that is my Fuji's original Fujita Belt saddle... Bike was built in Sept '74 as a '75 model and I bought the bike new (but as a discounted scratched floor model) in Oct '76. I've ridden that bike/saddle well over 50k miles since then!!

Brooks B-17
 

I’ve got the Brooks B17 on 5 of my 7 bikes. I LOVE that saddle. There is a Terry Fly on my Klein Quantum that was the most comfortable saddle I’d ever used... until I put the B17 on my tourer. They claim it takes 500 miles to break in I’ve put several thousand miles on both the Fly and the B17 wins hands down. I like the fly still but it’s covering is beginning to wear - I’ll be likely be putting the B17 on that bike when I replace the fly. I’m curious about the C17 for the Klein but reviews are mixed on it.