The difference is the drivetrain. I've got older bikes with shifters on the downtube, and bar end shifters. But man, I just got a Giant Defy with 2012 Shimano 105 shifters and it is sweet. I think if I ever got lucky enough to find a good deal on modern shifters and drivetrain, and swapped on to an older good quality frame it would be just as good. Once you go STI it's tough to go back.