Is anyone successfully using Scrivener for co-writing?

I’m co-writing a novel with a new-to-Scrivener user. He is extremely excited about the organizational capabilities of the software. But our workflow is becoming slightly annoying. We have a master Scrivener file in DropBox, and when we aren’t together we stay away from the file if prompted to create a copy, since this indicates the other is in the project.

Getting frustrated at how often we are working at the same time while not being in the same room, I’ve started writing in another file from which I take text documents then manually merge them into the master once he’s out of the document.

I suspect there isn’t a perfect collaborative solution…yet. But are there any other workarounds that might make my life a little easier?