Steve,
Nice job on the buff horn.
Never having flattened one, I would think that a horn off a mature bull would require a lot of thinning down.
Once you got it to a point where it was workable, it shouldn't be any better or worse than a cow horn.
For some reason, I have no desire to work on one again. I did some years ago using the natural shape and found it wasn't too difficult to do it that way. But I didn't cook it, either.
John