This seems to be a really simple need that we have. And I think that with all of the energy and creativity out there working on parts of this puzzle, somebody is going to come along really soon and create an ad-hoc project team space that will have all of this functionality and it will be cross-platform and the birds will sing and the flowers will bloom and happy days will reign on Earth. Or at least we won't have to use Word anymore. Which is almost as good. Troy Angrignon :: Do you want collaborative rich-text editing of documents? So do I. Alas, we are not there
Troy's starting working on a big project, and we had jointly been throwing some potential solutions back and forth on what works.
Like Troy, I'm testing the early access version of Near Time Flow. I can't say much more about it here except for this: it does do rich text editing, but it's not "real time", although the collaboration is still there.
Lastly, Word with track changes absolutely does not work reliably. And I've talked before about how email is not for file transfer. Could purple numbers be part of the solution here? (Or purple pilcrows, if you prefer)