This is great stuff!
I was wondering though, looking at the stack, if some parts couldn't be substituted with "lighter" alternatives? I'm assuming couchbase is being used for the changes feed and since you can't do adhoc querying you need "elastic search" for that, however wouldn't it be possible to replace both with just rehinkdb? Anyway I'm just speculating here, I should probably dig into the code.
Thanks for sharing this and keep up the good work!
Update: seems you'll still need elastic search for rethinkdb full text search [0]