Again, essentially what we do in concept. The dev side is a separate db (git could represent this), and once something is published past dev the record is copied to the production db (Riak in your case). The dbs have in-memory local machine cached versions, for speed, but also for reliability. You don't want your N machines depending on one db point of failure, so the local cached copies exist to mitigate that. (They receive updates via a multicast mechanism.)
I have some plans in this area, but I couldn't guess how to best fit into other people's workflows.
What might be nice is if there was a way to sync a git repository with Riak, and then Nirvana could just pull the relevant code from that. Seems like it would be the best solution, but looking into that- from looking at possibly integrating with a github API (do they have one?) to command line scripts is something I'm punting on to focus on the essentials.
But I do agree with your points!