You're reading in my mind !
I plan to post a new thread about this, to show that it is possible (I hope anyway !) and how to do it.
To be completely honest, I don't see that as difficult, and yes, I've been living in China for a while. ;-))

The Yamaha store should take care of the plate registration for me, I will provide to them all the necessary documents.
What is unknown to me right now is the process to change the insurance to the new bike, and the procedure to sell the Honda when I'll find a buyer. I especially want a document proving that I'm not the owner anymore of the Honda after selling it, not to have any liability if the buyer does something stupid with it. ;-))