I agree on the S4 - test rode it when I bought my Madone 2.1. While the ride was much more responsive and bumps were muted, I could not justify spending an extra $400 or so to shed 1 pound, yet downgrade from 105 to Tiagra. Don't get me wrong, Tiagra is good, but not the components I expect on an $1700 bike. I would have loved to get the S5, with the 105, but my wife finally stopped approving my budget increases.