I'm nearly done - the thing in beta right now (though offline at this exact point in time 🙂 ).
The particular problem has a performance "challenge" for the graph that isn't solved to my satisfaction. In performance tests I get "workable" but not "awesome" performance, while an SQL based prototype appeared to do "awesome" (at the expense of being more painful to implement and think about).
It may be that graph experts can shine a light on how to do it better, so I'll try to find a way to concisely describe the problem when I have a moment
Do you have an example of this sort of thing, to follow the lead of?