Brooks saddles, the B17 in particular, work better with a more upright posture. This is because the sit bones mold very well to the leather cover, providing a good deal of comfort. The mid ridge area of the Brooks saddles are rather stiff and, put more pressure on the perennial area than other saddles (though none are perfect).
I have not ridden the Brooks Swallow or Swift but, I think these might better suit a Tri rider from what I can gather. YMMV.
I find the Selle An-Atomica works pretty darn well for an aggressive riding position, molding to the sit bones while still providing plenty of perennial area relief when you down in the drops with the hammer down. Brooks is coming out with a new saddle similar to the Selle called the "Imperial". There is a discussion thread on it over at the Vintage forum.