I think I've seen something of this topic before, and might have even chimed in...
But Kieth... I'm guilty of doing just what you're asking about...
My very first commissioned piece was from a local maker I met at a show out here years ago: I had a small Taylor Aikuchi in 440c... Cheap, but the ideal size for what I was carrying it for, but I wanted a real one (Even back then I knew the difference between handmade and cheap commercial stuff, but I didn't know propper etiquette concerning the art of interacting with an artiste!) So I asked him to make me one very similar to it in cable Damascus... I still have it, he still remembers me and I honestly never thought I might offend him by asking him to copy something else that was of a very simple, traditional design.
My very first piece commissioned from a Master Smith was also a request to make a "better" version of a knife I had bought made out here by a local maker who apparently is no longer in public. I asked for their interpretation, in Damascus - and I have one of the finest hunting knives out there and if it was held up to the original, you wouldn't really recognize them as anything more than the same size and general profile... And again, it didn't even occour to me that there might be an issue with this...
And then I did it again...
But then I came across a thread a year or two ago concerning this very topic...
Sure wish this media and this forum were around a long time ago... Y'all would have educated me...
And then I wouldn't have three incredible knives!!!

LOL!!!!
However, I do think that I wouldn't be inclined to ask for a copy of something that had a highly recognizable style without asking first... unless the maker was no longer with us... For instance, in this case Kieth, due to the recognition factor of that knife, I might be hesitant, but as others have said, maybe a maker out there could forge you one close, with your mods and maybe mods of thier own... just enough that it would be yours...
Afterall, as someone else also said... How many different ways can you form an oblong out of metal that both cuts and is easy and comfortable to hold? Form and function, in this case, seems to follow a very narrow path...