Okay,
Drew, your your first statement makes sense and I agree with you in full! However your second statement I would like to interject on. If an unbiased buyer purchases a "Folmer" flash from someone in the community, especially someone with a lot of Graflex experience or has a wealth of parts, if the seller is trying to make an Inc. top look Folmer, of course they are going to shine it up, and add the Folmer parts. The rivet however would not be as easily changeable. So to presume that the few Folmer flashes out there that have a machined shiny rivet like an Inc have had their other coordinating parts replaced, would not be so far out. Not to say these "transitional era" flashes didn't have a few overlaps in rivet styles, that could be a possibility for sure. But I would say a vast majority of this machined rivet style is from true Inc. era Graflexes. And I don't believe it would be preposterous to think that the FEW anomalies we've seen ("Folmers" with a machined rivet) could have very well had their parts swapped and sold to you or any consumer as a "Folmer" top, Intentionally, or unintentionally. But since it was sold to you as "Folmer" perhaps our minds might be more biased towards the idea that it is a true Folmer, when it could just as easily be a nice Inc that the previous owner swapped parts to have it fit in better with the Folmer look. All but the Machined rivet of course

The Graflexe's purchased nowadays have most likely seen many prior owners before it got to you. This being said, if it's being sold as a true Folmer and it has that shiny rivet, don't rule out the fact it could easily be a nice Inc or transitional anomaly with parts swapped out.
That being said this discussion is great, but I also don't want to derail Nate's awesome thread specifically about Luke's ANH hilt. Though it is great info to open the minds of any new builders of this hilt to decide for themselves. Perhaps I'll go ahead and start another thread specifically to document photos and conversations about the beertab rivet, so we can compile a large number of photos to more accurately portray data.