I'm the author of Phoenix. I'm glad to hear you're giving it a look! I spent a lot of time thinking about the WS layer and fallback support. Ultimately I settled for standard WS with a small multiplexing layer on top. For those that need fallback, they can drop in websocket-js (flash fallback, compatible with native WS api). Have you taken at look at this for your fallback support?
https://github.com/gimite/web-socket-js
Phoenix is still far from 1.0, so any and all feedback is welcome.
I'm new to Elixir (and FP in general), but I really like the language. I came across a couple of youtube videos on Phoenix , and it looks really nice (reminds me of Rails). I think something like Sinatra would be even nicer, for 2 reasons:
1. the standard these days is to have a rest api serving json to web/mobile clients, so a Rails-like framework seems overkill
2. Pretty much all my friends who are learning web dev on their own, find Sinatra/Flask way easier to get started with than Rails/Django.
Regardless, Elixir (and Phoenix) is a great leap forward compared to the other options for building concurrent, reliable servers. I hope more people try it out before falling for hype/marketing (cough node.js cough mongodb cough cough)
Phoenix is still far from 1.0, so any and all feedback is welcome.