My carbon bike is a Madone WSD, and the geometry is not aggressive. My tires are 700x23. I like them at 110 psi but I could easily drop that to 100, and probably could go to 90 or lower without pinch flats. And I really don't have problems with pain anywhere since I got a bike that fits me.
Also I looked at a Madone WSD 3-series a few weeks ago that was a 2011 model, and the frame had various holes in it for adding packs and racks for touring. Whereas my 4-series did not have those things. So I wouldn't be surprised if the fork on the 3-series allowed for wider tires, too. It was on sale for < $1500.

