I did some collaboration on a pretty simple project (Mosaic Maker) in Dreams a few months ago. Just creating modular components that could integrate with a larger scene was somewhat tough but not terrible. Versioning them and updating them was somewhat harder. I think as groups get better at this, they'll get the hang of it. But the sharing layer built into dreams was pretty bad at the time. If you had a few versions of different dependent components, you could hit bugs preventing you from working on them. If your component used someone else's (which is encouraged as one of the pillars of the game), you might find you're blocked from releasing if the creator restricted that component. Or sometimes the opposite: people didn't get credited for what was clearly theirs.

Overall I'd say that collaboration patterns could work if you had a group that knew how they work and supported them.