I was looking at two Specialized Roubaix frames, one 56cm and one 58cm since I seemed to be on the line between both. I initially felt the top tube of the 58 seemed more comfortable (this is my first road bike in quite a while). The LBS talked me into the 56 saying I looked to be in a better position on it. Boy, am I glad I did--after a month and about 700 miles, I am not only comfortable, but contemplating moving the stem angle down a bit more to get into a more aggressive position--I wouldn't have had that choice on a bigger frame. I say go with the smaller.