Interesting question.How can bamboo rods be consistent in their casting characteristics? If one tries a bamboo rod from an established maker and really likes the action, how can that person be assured they will get the same action and feel from another of his bamboo rods? Being a natural material, there must has to be variations from one piece of bamboo to another, that could take many forms. How is that controlled? With graphite a known and repeatable formula is used to make each rod nearly identical. I know the easy answer is, "That is what gives bamboo its personality - each rod is different." But isn't that just a cop out when you are paying a minimum of a four figure price tag and you feel the action is different than the rod that influenced you in the first place?
I guess one could say the same thing about flies. Each is hand made of both natural and manmade materials. (wink)
I'm no bamboo expert but I think the rod maker selects the seasoned culm to be consistent and then shaves that down to the thousandths of an inch tolerance.
It comes down to how fine a proprioception the angler has. Could I tell the difference between two bamboo rods that are identical models from the same builder. Probably not. Could a bamboo rod owner tell his personal rod from an identical model? Maybe so maybe not. I really don't know.
I'd like to hear from bamboo owners.
I'd also like to add a second question. I am going to turn your question on it's head in that I believe your question contains a presupposition that if the rods are not identical, then they are somehow less valuable or less useful than a "consistent" graphite rod. Therefore, I am going to ask whether it even matters if they are not "identical"? What I mean by that is, if there is a slight difference, then each rod is unique in itself and does that not also have some value?