Originally Posted by vasuvius

Unless the discomfort is really bad and means a really poor fit (blame the LBS), a 100 miles or so is simply too little to start fine tuning the fit.
It takes me 400 miles to break in a new saddle and I have yet to meet a saddle that my butt disagreed with.
Every single change, and always only 1 change at a time, should at least be tested for a couple hundred miles unless it's really bad early on.