I can't answer the specific questions about which saddle, but both DH and I are currently on trial with Brooks Cambium saddles. They're rubber/fabric (vegan) and don't have the break in of the leather saddles (or the worry about rain ruining them). Brooks offers a 10 year warranty on them with registration. I actually got mine 20% off at REI (but their regular prices are higher than my favorite Brooks supplier - Wallingford Bike). I'd look at the dimensions and see how close the Brooks saddles are to what you have.
So far, very nice. I'll try to remember to report back in a while. DH has a C15 on his road bike (skinny), and I have a C17 on by Brompton. Only downside for me so far is I now have to cable lock the saddle (it's a quick release seat post).
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