The difference is the racer tweeks his own suspension and has the ability to modify because of experience. Most of our "custom" builders are not engineers, racers, and usual are just assemblers of parts. They risk the lives of any person that decides to ride their craptastic creations, no matter how good looking they are. I have no problem with someone building a bike, just don't sell it . There is no comparison of these custom builders and someone like Godet. His designs are proven, developed and executed with meticulous precision. He is a "custom" builder, but one that knows what he is doing. I did a quick calculation from the picture of the exhaust on the Falcon, and it does not follow Phil Irvings calculation for the optimum length for a open exhaust pipes on Vincents. If they can't get that right, then who knows what else is wrong.
Merry Christmas, Dan