I have never had a custom frame built for me, but I want to relate an experience from Saturday.
We took a friend to the LBS to buy her first road bike. We went through every bike that was a remote possibility. Nothing was even close. They were so far off that anybody with experience fitting bikes knew that a stock frame wasn't going fit her no matter what brand or model. The LBS hauled out a Serotta fit bike and set her up on custom geometry and magically she looked comfortable. It was amazing to watch her body go from awful contortions to a relaxed proper fit. The friend ended up ordering a custom steel Seven. Every time I have spoken with someone with weird fit issues that has ordered a Seven they have waxed eloquent about the efforts that Seven goes thorugh the fit the customer.
Turned out the friend has simililar geometry challenges to another customer of the LBS and yesterday I ran into the other customer. The woman was about the same age and body type and had gone through numerous stock frames without ever having a good fit. Her comment was she finally had a bike that "just floated under her." I've always been impressed with Seven's frame and workmanship but to see the fitting process in action was incredible. I've always thought that custom frames were a good thing, but now I think they're a wonderful thing!
Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.