I have both, and they are very different.

The B17 is more dipped from nose to tail than the Swallow, and needs to be positioned at a nose up angle in order to get the sit bone area flat. If you don't do this you will feel like you are sliding forward (a lot) all the time and overweighting your hands. Because of this, "most" people consider the B17 more compatible with an upright riding position.

The Swallow is still dipped, but much less. It's marketed towards a more aggressive riding position.

That said, I have a Brooks Team Pro Classic on another bike, and if I had it all to do over again, I think I'd put the Team Pro on all my bikes instead of the B17 and Swallow. The leather is much thicker which creates less of a "suspension" effect than the others. Hard and Firm, but I've come to prefer that. More importantly, it is pretty much as flat as a board. Not just from nose to tail, but from left to right at the sit bone area as well. That seems to agree with my butt. It feels like it would work for any riding position.

Saddles are a really personal thing though. Lot's of people absolutely HATE the Team Pro and Brooks saddles in general. If there is an LBS near you that allows test rides, I'd highly recommend that before a purchase.

Dipped B17



Flatter Swallow



Flatter Team Pro