I don't co-write with anyone, but I do access Scrivener files from the same location from multiple computers. If you're going to do this, the thing to remember is that the most recent update will trump whatever was saved last, so if you leave it open somewhere, edit from somewhere else, and then go back to the original doc, closing the first window down might erase your edits depending on your Scrivener settings.
If you want to do this, make sure you edit at different times and always close out the files when you're done (I also recommend having each writer's client store its own backups in a folder somewhere locally in case of a mishap).