I don't see much relationship between the carving on the Honaker piece and the BBR/RCA 145 pieces, either. However, may I gently remind the members here that the attribution to Honaker is not based on carving design, but on architectural and construction details? Chip carving doesn't seem to have had much of a following here in the US, and folk-art carving is pretty rare on rifles in general, even in places where it was common on other objects, so it is quite possible that it disappeared simply because the customer base didn't like it. Stranger things have happened.
Seems to me the cheekpiece construction is more significant than the carving. I've seen a German smoothbore with a near-identical cheekpiece, which the owner believed to have been made in the same shop that trained the guy that made BBR, and I think that if one wanted to challenge the Honaker attribution one might ask why he was still making this very niche style of cheekpiece in 1771.
On the subject of attributions based on small details:
Once upon a time, I went and got a master's degree in Medieval history, specializing in the period between Late Antiquity and the end of the Viking age popularly known as the Dark Ages. As so happens, this period has extremely few written sources, no first-hand accounts, and depends a lot on archeology. Accordingly, anyone who works in this area gets very familiar with the strengths and weaknesses of archeological sources and has to become good at looking for small clues in stuff like poetry and chronicles written with obvious agendas generations later. An off-hand comment or the writer's assumption of knowledge on the part of the reader can be quite illuminating with these kind of sources.
Now there are many good historians in this hobby, including several on this board (*waves at Eric Kettenberg, Bob Leinemann, and Shelby Galien, to name some that spring to mind*), but so far as I've seen Gusler seems to be fairly unique in that he notices as significant small things like an early rifle specified as having brass mounts, or a pattern of rifles listed together with a set of accouterments complete except for powderhorns. That is close reading the way Medievalists do it, and I'd like to see more of it. Like everyone else, he has his biases and idiosyncracies that have to be taken into account, and I certainly don't expect people to accept everything he says without question (I don't), but I don't think that his overall approach is out of line with standards of historical writing (What he doesn't do is use the usual verbiage of uncertainty that historians usually (see what I did there?) use to insulate themselves from their conclusions. That makes him easier to dismiss as a crank, I think.)
Unlike the sciences, to the extent that there is any progress in historical knowledge, that progress is made primarily through re-examination of old evidence rather than the discovery of new sources. Looking at available data, drawing conclusions, and then using those conclusions as presuppositions to make more complex arguments, only to have the whole edifice torn down and rebuilt when someone else notices something you missed or assumed is what historians do, ladies and gentlemen. Eventually, at least in theory, an framework arises that proves sturdy enough in the face of criticism that it can be accepted as true. A healthy dose of skepticism is an integral part of the process, but unless someone is willing to go out on a limb and draw conclusions based on the available evidence we will never get anywhere.