Originally Posted by Campag4life

Saddle shape makes a big difference in setting up bikes equivalently. Simple reason is...we don't sit in the same spot not only vertically but fore/aft on a different saddle. I just replaced an old Toupe saddle on my bike with a new Toupe..same width. Specialized has changed the Toupe saddle shape over the generations...some say for the good and others not so much. I am breaking in the new Toupe and learning to like it. It definitely is different. But I am riding it farther back than my original Toupe. So I ended up removing the 130mm stem and put a 120mm stem on my bike.

So setting up different bikes is tricky if the saddles aren't indentical. Saddles can be shaped differently of course but also can deform differently under load.