Hi Miranda,
I have a couple of B17S saddles and a B17.
You asked if there was any reason (besides saddle adjustment) that a B17 might be "better" than a B17S. Besides what CA_in_NC and BSG have said, I think it comes down to fit. The B17S is wider than the B17, and it might be too wide for you. It also has a different shape -- the wide to narrow "transition" is more pronounced on the B17S than on the B17. You may have seen on some threads that some people prefer T-shaped saddles vs. Pear-shaped saddles. In my opinion, the B17S is more T-shaped than the B17.
Basically, it's a matter of individual fit, which you won't know until you try it for a few miles. (Yah, that was really helpful, wasn't it?)
I've ridden my Brooks for many, many miles -- in the drops, on the hoods, on the tops -- it's all good! Personally, I think one of the ultimate tests for a saddle is how comfortable it is when riding an indoor trainer. You don't get any breaks by waiting at a stop light, and you don't do a lot of climbing while standing on the trainer. I did a lot of indoor training on my Brooks Team Pro S (basically the same as the B17S), and it was instrumental in keeping me comfortable so I could log a lot of miles on my trainer.
- Melissa
I'll get back on the bike soon, I promise!