I have once and it was fantastic for me. I went to Dr. Jason Glowney and his fit guy at CU-Boulder. I think Dr. Pruitt is also there, and is a pretty famous fit doc. Among other things, they fit me with pedal extenders, moved my saddle and cleats around, and raised my handlebar. The difference was pretty impressive. They took into account my flexibility and as they gets better, I can drop my bar by a few mm. It was very helpful from a comfort standpoint, and it is much easier to go past the 30-mile mark that was my max before. They also said I could make a 56cm or 58cm bike fit, since I have used both and I am kinda in the middle. So I stuck with 58s and simply use a shorter stem and avoid the toe overlap I get with 56s (size 12 feet).