I enjoyed that - it was presented well and I thought the use of
ReactiveDict was good. However, you explicitly ruled out Mongo, whereas it might be worth considering a client-only collection as an alternative.
I recall a blog post about a year or so ago in which the basic approach as you presented was discussed (it may have used
Session - I can't recall). Annoyingly, I can't find it now!
Edit: Found it. It wasn't quite as I had remembered it, but it may be useful to compare approaches: