Kwantani, the Legend series frames had a "square" design, meaning the top tube equaled the seat tube on sizes 56 and up. I worked at a stocking Serotta dealer for a number of years and rarely had to go custom to get a longer top tube. Race frames, ie Italian frame design influence, typically have a longer top tube. Using a 57cm as reference the Serotta has a 57cm TT in the Legend series. A "race" frame may well have a 57.5 to 58 TT. The 57 Legend has a head angle of 73.
Back when I raced a Miyata Team frame the ST was 56 and the TT was 56. Fairly standard design back then. Again, if you have been riding a frame with a longish TT the Legend Ti might feel short, but it really isn't anything out of the norm.