Work on this slowly but surely progresses…
Today I have added the possibility to specify a transformation_function that you can use to alter the state that your GenServer has before it is persisted. This is for instance useful if parts of the state actually ought to be ephemeral.
One of the things I am currently conflicted by a little is configuration: Currently the configuration of the GenServer is part of its identity. It is set when the GenServer is started, and is part of the symbolic PID that is passed around. That is probably suboptimal, if you want to change how an already-existing persistent GenServer behaves.
However, since some of these settings alter the way the PID lookup happens (and control things like ‘how-to-restart-if-persisted’), I see no other way to do this. 
More (hammock-driven 
) thinking needed…
