Just to add to Downtube42's thread, I've been experimented with a bunch of saddles lately. My new bike uses a 7x9 seat rail mount, limiting my choices.
On brevets, my bottom would long for my B17 or Aravis.
I bought a Brooks C13 158mm and despite only 20 miles on it, put it into service on a very bumpy (think bombed out Beirut roads) 400K and it was fine and even good riding on aero clip ons although mine are not very low because they serve really just for comfort, they are level with the saddle. It seems like the Aravis in that regard, probably not as comfy sitting straight upright as on the B17, good at 45 degrees at least for me. An advantage of the C13 (there is a C15 and C17, not sure the difference) is the saddle covering is a textured, rubbery material that should be fine in rain. I took a risk, it was discounted at $136 online but so far it seems like a keeper.