I remember reading a similar discussion on this forum years ago, in which the general consensus was that you could interchange parts within a machine to your heart's content, but if you packed an entire spare chassis or started replacing large portions (>50%) of the current, possibly severely damaged, one, it constituted a different machine. I still consider that to be the case.

Not kicking up a stink about what happened at the champs as it's been and gone, but I think it's something that needs to be given more consideration, especially as it's a particularly toasty subject