If you've used Editorially and enjoyed it, I'd like to recommend my own application that I am currently developing called Typewrite ( https://typewrite.io ). Though it's only been in development for about a month an a half, it is relatively inexpensive to run and I don't plan on shutting it down anytime soon.

It has live collaboration like Google Docs, and a simple interface like Byword, iA Writer, or Editorially. I'm working behind the scenes to add features and documentation and plan on releasing updates for it every so often.

If you are interested in seeing why I created Typewrite, please read the first blog post at: http://blog.typewrite.io/2014/simplicity-in-real-time/