Honestly, as the person who is ending up having to do the RethinkDB migration... it's the lack of an AWS hosted solution that killed it for us. Even the import is a great experience and moving to MongoDB wasn't too bad (after a bit of cleanup)
Interesting, RethinkDB was really easy to setup. Three EC2 instances (cluster), install their apt repo, and install. There were a few config options[1], but really minimal and clean.
