Exactly - it should transfer device ID, and everything that is connected to that ID (widgets). I think that only thing that can be really difficult is transferring triggers and scheduling. Triggers can also contain more than one device and/or widget, so that is, in my opinion, hard to transfer. Schedules are also a bit complicated, but, again my opinion, somewhat easier than triggers.
So, if it's possible to make transferring just for devices and widgets, so be it