Sorry im a litle late to the thread,its been gorgeous here lately.But these guys could not have given you a better explanation.Of course my world doesnt revolve around undiscovered arcade revisions,but its just cool to know another revision is out there,waiting to be discovered.
Its probably the same reason why I like the little differences found in Famicom games vs their NES conterparts.Its just cool and interesting.Sorry I cant explain it better,its just either you get it or you dont.