The problem with custom frames is that they may not fit. I personally feel that you should know what fit you require before going to a custom frame. There are lots of peole who didn't get what they wanted out of custom frames. I break it down this way:

1) newbies who go into a frame shop, it should be simple for anyone to see them coming through the door and pretty much have the frame picked out for them.

2) Opinionated semi-seasoned cyclists who don't know what they don't know and want a bunch of stuff that is incompatible, and the whole thing gets muddled and they get the wrong bike, insert a physical disability or two; lots of previous bikes all accross the board none of which previously made them happy; some oddball technical needs; a body that is betweem sizes; no face to face meeting...

3) well seasoned cyclist who have riden long miles in various sensible bikes and know what they need. They should be able to confirm where the fitter is going and raise red flags even on a long distance fit if something seems to be going wrong.

Even face to face fits can go wrong if the person isn't all that knowledgeable, or they are only experienced on one kind of bike, but not touring bikes, or there are unusual technologies at play, or there are physical disabilities involved.