That's correct. If on Heroku, Faye would run in it's own dyno process, while Pusher is a commercial product. Sync requires a pubsub server to talk to, so either

That's correct. If on Heroku, Faye would run in it's own dyno process, while Pusher is a commercial product. Sync requires a pubsub server to talk to, so either is a must. I suggest prototyping out with the Pusher free plan if you just want to throw something up to experiment with.