How about "never."
Here, Facebook, Tulsa Wanenmacher show?
never.
Seen one guy drag around what looked like a Model 14 with a poorly done G10 "jade" handle asking if it was legit. That was a quick and easy answer -- "uh, no. not a chance."
One of the Behring re-handles? not once.
I don't get the exposure you do, given your position vs. mine (spectator/customer), of course.
That is odd, because I read the same things you are reading, and I can count on a "is this legit?" post it seems pretty regularly, not necessarily Behring, but other pieces that may or may not be are altered. I suppose in some respects maybe it is a good thing, because newer guys are getting into the hobby. You are in the "circle" and are familiar with re-handles, there are many newer folks that are not.
Look no further than the previous page in the thread for a post from aaron stating his thoughts as he had his doubts!! So you don't have to look very far to find a post.
Using your example of the 14 with the G10 handle, what if it was one of the stolen blades put together by a fellow in Florida with that or similar handle material? 99% wouldn't know the difference until it was pointed out to them, but you wouldn't know by looking at it. The reason I know about them as I saw them delivered in a duffle bag to a show probably 25+ years ago. By memory I would estimate 20 or so 14's and 15's (16's maybe?) delivered and eventually sold as "rare" handle material. I saw one on ebay a couple of months ago.
Yes, I have run across this at shows, and have had some Behring pieces sent in for authentication, and the folks believe 100% that they are made by the Randall shop and are "one of a kind", and will even argue about it (one guy said I was full of shit) when you tell them sorry, it was done after it left the shop.
One sure way to take a guy out of the hobby is him buying a knife that isn't what he thinks it is. All I am saying, is the re-handles should be identified in some fashion, and that is supposed to be what is going on.