Well to be fair I think Bandai knows that unlike Rider Fans...Fans of megaman don't mind buying multiple colors of a similar character. Hell they beg for it.
I think people are starting to get too paranoid about that.
The only form of X with original molding I can see being exclusive is his X4-X8 ultimate armor(since it is mostly a recolor of the X4 armor). Maybe Gaea armor too? That doesn't seem to be too popular.
Parts, are, indeed interchangeable to show X's progression in getting the armor (apparently, X went through Sting Chameleon and Chill Penguin first. lol)
...I'd actually like D-Arts of Mavericks...THOSE I'd collect!
After his body went all ka-blooey in X, X was challenged by the X-Hunters, Violin, Serges, and Agile, for Zero's parts that they took back to revive the deceased Maverick Hunter as a Maverick.