We're a Trek family (including 2 Madones).

I think you should let fit be the guide and maybe invest a couple hundred $ in a complete fitting by an experienced person. (there's a thread on her about that). It may even be that there's a better option.

Case in Point: Silver has an '07 58cm Madone 5.2 (with 10,000 miles on it), but in a subsequent fitting, the fitter suggested a 56cm would have been better.

Happy Riding

PS: Keep in mind that Carbon is fragile. If you're not experienced, a fall could damage the frame. Maybe you'd be well served to consider a higher end/non-carbon frame.