[pmontra]

I've been running it in production since the first days of the year with a small new application. No problems whatsoever writing, testing, deploying and running it. I don't expect particular problems upgrading Rails 4.2 applications.

I didn't use ActionCable because my application doesn't need it. I experimented with it since the first version, which I plugged into Rails 4.2. It had some quirks that were fixed. It works well. There is obviously code to write in the client to handle the websocket but it's pretty much standard boilerplate. I expect some gem will appear implementing it in some clever helper, except the code we really have to write.