I'm working on an implementation over at https://github.com/aji/charybdis-migrate (No code yet. The code is all on my hard disk and is half-written, but my approach is outlined in the document.)
I want to hear people's thoughts so I don't waste my own time putting together a proof-of-concept in charybdis-migrate.
Huge +1 for this spec - seamlessly being able to push people off a leaf so it can be rebooted is a very cool idea.
That said, I really think this should be changed to leverage