The B17 is a wide pear.

The B17S is the same pear shaped saddle with a shorter nose. The transition area (the one that chafes if you need a T shape or feels too abrupt if you need a pear) is the same.

There's a nice picture on the wallbike site that shows the saddles in comparison from a top view.

T or Pear refers to the transition from sit to nose, not length of nose.

If your measuring guy was accurate with 110mm for your center-to-center, then you will probably be happy with a B17. If you don't like it, you have 6 months to send it back to wallbike.com