Doesn't seem like there's an easy way to do p2p chatting without hitting your server (often) with a new list of 'friends.' Any chance of supporting something simpler?
Our API lets you send individual friend list updates from your backend, and we're actually working on a web-hook based way of handling friend requests: if we need to verify that user A has permission to talk to a new user B we can POST to your web server and then update the friend list, or (if you use Parse) you can specify a Parse query and we'll look up the friends that way.