Andrew, a question.
One of the things I like about my B17s is that in really really hot weather, I do find a leather saddle more comfortable because of the breathability of the leather, and the fact that when you sweat a lot, the leather does absorb it, so I feel less sweaty down there in general compared to seats Ive used in the past.
Is this a difference you found in this rubber topped c17?
That is a good point and I don't recall any issues but then I don't think I got much summer riding in with it. Now it has gone or is going over to the MTB it will get less. Most of my touring is in winter or the cooler months here due to summer being way to hot.
Sorry cannot help much
Oh, do you find the "give" factor (flexing wise) similar to a leather seat, thats another thing I like about my B17s, the give they have takes the edge of things and certainly contributes to long term riding comfort along with the basic thing of them taking to your specific shape.
What I can say in this regard is I didn't notice any discomfort with the saddle over the Brooks Team Professional that I took off the bike so I would say that the flex was acceptable. It will be interesting to see how it goes on the MTB in this regards. Unfortunately my next tour will be on the Surly so it maybe awhile before I can really test this out.
Not much help I am afraid
Andrew