Funny timing- I actually just ebay'd a C17s last night. I went with the s model because it is 1cm or so shorter than the b17 and i am waiting for a b17 to show up too. A couple of my current saddles are the same length as a C17s and ive never complained about those saddle's length.
The winter trial and error of swapping saddles out on my trainer is about to begin! I snagged the C17s for $75 and its basically new, so if its terrible for me, hopefully I can sell it and not take much or any of a hit.