Just to provide an update on my previous posts above, I spoke to a Samuelsohn representative about the differences between the "Gable" style coat (i.e. non-Rosen) and "Ashton" style coat (i.e. J.P. Tilford @ Rosen). He said that he couldn't get into specific measurements, but he said that generally speaking, the ashton had a slightly shorter coat length and slightly trimmer waist compared to the Gable. This makes sense, as they seemed to be similar at a glance. But good to hear it from the horse's mouth.
I'm still waiting for Harry Rosen to complete the alteration work, so I haven't picked it up yet. Looking forward to it, though.