> Reading the source now (just woke up, sorry!), the new protocol thing makes sense

Good :-)

> I'm not sure what to do with the waiter argument or how to handle that.

I'm not sure. Apparently it's used for create_connection(), so perhaps it's not necessary here? Perhaps Victor or Guido can give some insight...

> What I'm really trying to think of here is how to handle copying of state

Well, there shouldn't be any copying necessary. The user just continues using the same protocol instance; it just calls a different transport.