The Progetto X2 Air chamois is fantastic - I just rode a century with one on Saturday. The Free Aero Race is my new favorite long distance bib.
As for fit, they are more snug than my equally sized giordano bibs and at least one size smaller than my craft, descente or sugoi bibs but only maybe a half size smaller than my pearl izumi pro shorts (one size smaller than my elite shorts though, go figure)