This issue came up in the past, I posted, someone else posted a link into the BATF web site to a section commenting directly about T/C interchanges.
And, yes, it seems rediculous that two components that are exactly the same except for the number stamped on them are considered different in the eyes of the law. This is why when I got my Encore I got the pistol version to start with. I've thought about selling it a few times since it's mostly just a safequeen, but still think about getting a second barrel for it. And, yes, I'm one of those people you've heard rumors of who have a T/C and only have one barrel for it (oh the shame of it all).