Two very good replies above. Agree with all. But neither mentiond what the OP asked about: "Custom" frames compared to his production Lemond. Here the common belief is that a custom frame (and by custom I mean dimensioning specific to the rider, not an off the shelf geometry) will provide some fit or purpose advantage that a production frame won't. These advantages could be "better" body positioning, nicer ballance/handling with the needed fit or component/braze on arrangements that aren't common. All of these aspects are independent of the tubing choices. But tubing choice can effect the over all package. A touring bike with too flexy a top tube or fork come to mind. For most riders and the general sport recreational (weekend club/wanna be racer) riding public the two above replies are spot on. Andy.