Resurrecting this old post--I remember this being a specific point of concern with the old Abbyshot coats. The V1 had a rain resistant coating which made it a great, practical raincoat--but, the result was that it didn't wrinkle, crumple and bend correctly. The fabric flow was wrong. They corrected this on the V2 and did away with the coating, and the result was a less practical piece that looked a lot more accurate.This is all really looking great! My only comment is that I feel certain that the original had a thin layer of quilting under the surface (or between the outer layer and lining. All the stills posted (to me) indicate this. I see this serving two purposes: bulks up the profile a bit but doesn’t add weight. Probably a 1/4" layer of dacron. And plus, it was the 80s, right? The "look" harkened back to the 30s-40s, but everything back in the 80s was silky and puffy to some degree!
Beyond the 80s angle there are a few practical reasons that might come into play: It would allow the outer layer to be a little softer and thus flow more easily.
One final thought: they HAD to had given the whole thing some kind or moisture sealing given that it's raining the entire film.
I was under the impression that the general consensus was that the film coat wasn't coated and didn't have any sort of rain-proof finish. I would personally opt for accuracy for my own coat, but it's true, an alternate rain-proof fabric could be an interesting choice if the true goal was practicality.