Good points, but the differences between Ariga+Iwamoto and Capcom's are stylistic; a significant change would be removing or altering an aspect of X's design, like the jewel on his helmet (for example). Hence why the box art and Nintendo Power have been excluded.
As for iX, I'm hesitant to include him because, though derived from X, he's not the same character as X--and I hope to create a separate page for the copies throughout the series, so that feels like a better place to put him. (The same goes for Copy X)
...And no one's answered my question about Unknown X. ;_; EDIT: OK, it seems that "Unknown X" is just another name for Not Ninja Butterfly Cyber X. Ghar.