Other than I now know for sure that you don't know the actual costs involved.
I want to say that although I might be mistaken, your post seems to indicate that someone who questions the costing of one of these custom pieces must not fully "appreciate" or "understand" them. Maybe that was not intentional, but that is the way the post came across to me since you made reference to those who appreciate/understand them more than once. For reference, I have seen enough in various watch factories and at places like Dufour's atelier, and also done enough finishing and assembly work on my own to say that I think I understand what goes into a custom piece like that. I also work in a manufacturing environment that requires tolerances on products much tighter than there would be on any wrist watch, so I completely understand the concept that "more goes into this than appears on the surface."
IMO this question, and any comment I have made certainly, had nothing to do with "Are they worth the money?" but more to do with "Why is X more than Y?"
Maybe some here are not comfortable because discussions like this are not always in the Purists line of thinking? I can agree to that but since the question was asked, I tried my best to give my perspective as others did. I've learned some things and IMO that is always good when a discussion results in learning.
We can debate what is more complicated to make and what takes more time or not until the cows come home, but really that information on it's own isn't helpful in understanding the price someone charges with any certainty. To me the watchmaker has complete control over what he charges by how he values the time put into the piece. We can say "we think it's more because of the work involved" but none of us really know enough details to be sure I suspect. Is the time an influence on the cost? Possibly, and I would even say it's likely, but I can't state that with complete confidence.
I think there is a factor of "what the market will bear" impacting the price charged.
In the end I would be happy to own either the Smith or the Dufour.
Thank you for the discussion.