The magic number: 1-888-731-3537. Bill (or Diane, but most likely Bill) will answer the phone.

When you talk to Bill, tell him what you currently ride and tell him how it looks compared to the B17 and B17S. Tell him your sit bone measurement. Tell him what bugs you about your current saddle. Tell him how you like to ride. He is a huge resource. He (or Diane) would be the best one to help you decide between the B17 and the B17S.

Also be sure to tell him if you like long-nose or short-nose saddles. And don't be afraid to tell him your budget. I told him my budget straight away, and he made absolutely no attempt to sell me something beyond my reach.

With a 6 month trial period, you really can't go wrong!

(for all I know, the B17 has a more abrupt transition than your current saddle, and would solve your chafing problem. Best compare the 3 saddles and discuss it with Bill or Diane. For example: I ride a B67, not a B67S)