The blessing and curses of my first bike fit...

[sjbraun]

Even if you're fitter is spot on, its a big jump from a fit plan to an actual bike. Working with a builder will allow him or her to vary tube selection in order to design a frame that rides how you want it to ride. So no, its not just about looks. Remember also that a production frameset in any given size is designed to fit a wide variety of riders. Take two riders, both are six feet tall. One weighs 140 pounds and the other weighs 250. Both riders "fit" a 58cm frame, but the same frame will ride very differently for these riders. That's the beauty of a custom frame. It's not all about fit, that's only part of the equation.
When I was talking options for my Breadwinner I asked about using a Columbus Max toptube, (for no other reason than I think the bi-ovalized top tube is freakin' sexy.) Ira, who knows how tubing selection translates into ride characteristics, very politely told me my idea would not work. So, again, work with an experienced builder, you get so much more than a bike that fits.