Yes, but not well. I'm using a commit-style approach to synchronize clients, so the document is never sent as a whole. I might be wrong, but I don't think couch can do that on its own. Even so, it gives me an extra layer of control, which I like. I considered making a CouchApp, but I didn't want to feel restricted.
I'm not that familiar with CouchDB-only apps but it seems to me that with node you get access to any number of other libs/technologies you may need. What if you want to aggregate a twitter feed? Connect to MongoDB for logging? Memcache? Do some image generation/processing? Websockets? Etc.
