It's really great to see perpetual interest in collaboration on LaTeX documents. I hope you have great success (not sure I have a use for it now but will keep you in mind if I ever do). I also expect to recommend it.

Unfortunately a lot of my own documents are really hard to handle with editors -- I tend to write very long documents split across multiple source documents in a tree for easy management. I wonder if there is room in an offering like this for something more like an online IDE rather than just a editor for a singular file.