This is all speculation...the only one who has the answer is Yamaha.
Anything else is just a guess, supposition, or an assumption.
But they are all probably
plausible...just not
provable, and until someone from the marketing team, or a person in a position to actually know the entire true answer, presents it here, it will always be a topic without an end.
That's why this type of topic usually gets a high number of posts.
I'd say Russ and KingFrog would be the closest, but that's just an educated guess from my own experience...and, like the others here, I can't prove it.
At this point, I'm rather bored with the whole thing...it's been so over-discussed, and never solved.
So keep guessing and maybe Genny will get the prize for having the topic with the highest number of posts.
Ian