Based on the info you provided also look at this: Is the 56mm Specialized measured from center of BB to Top of Seat tube or center of top tube? Same with the Cervelo. Find out exactly how many milimeters you would be gaining from the change of frames. For instance your Specialized might be measured from BB center to center of top tube, and the cerevelo might be measured from BB to top of seat tube. This means that both frames might be more similar than you think! Plus 2mm isn't exactly very much unless thats all you need, but remember your seat tube is already up as high as it will go on a 56! Maybe 60 will be more your size. I went through 3 frames before I found my somewhat perfect fit.