Reading this discussion reminds me of several times in the past when this question has come up. Reading this thread I'm reminded of one thing especially from many of the responses- not getting your desires in writing with the gunsmith to be sure he is capable of following your instructions exactly- or as close as he can make it . Also, not doing enough homework before hand on your own to determine what each manufacturer barrel contour actually means for weight and size, what twist rate you will need for the bullets you determine up front, what stock design you need for drop at heel and toe, etc....
In order to get a custom you will be happy with all these decisions have to be made ahead of time and communicated to the gunsmith. Trusting a gunsmith to read your mind is a recipe for a poor fitting, heavy, disappointing rifle. Just about the only way to get to this point is to handle a lot of rifles until you know exactly what you want.
I've also found some gunsmiths are great at the details, but poor on the big picture. Others are good at the big picture but poor on the details. To explain, I've had smiths who build a great feeling rifle that fit most of my criteria, but the finish would be crap or the barrel channel would be cut sloppy. I've also had smiths that did great work on stocks, finish was great, but the barrel would be too heavy or action wasn't as slick as it should be or stock wouldn't fit properly even after exact specifications were communicated.
Finding a gunsmith you can communicate with and has the same idea you have about rifles is invaluable. If a smith doesn't seem to be listening to what you have to say or is continually trying to convince you to do things the way he prefers, you need to find another gunsmith. Been there, done that....
Bob
