I just set up a refinery thing for my game Concierge, using per-person download keys. This worked well in general, except that the game is an embedded web game, and so upon visiting the key page, the user is confronted with a message saying that there's nothing for them to download. Which is true, but they don't need to download anything!
Apart from this I'm really liking Refinery so far. :) (And if anyone on this forum wants to join Concierge's refinery, and is up for giving lots of feedback, let me know.)