Originally Posted by Dial_tone
Exactly. My new frame has a top tube that is 2cm shorter than my previous one; however the actual distance from from seat tube to the center of the handlebars is mysteriously 3cm even though the angles are near identical. I can go to a 13cm stem and a 25mm setback seatpost but that still leaves me 1cm short. Hence the need for longer saddle rails.
I'd be suprised if most sleek modern saddle designs don't give you that extra 1cm of rearward adjustment over your present saddle.