This is one of those \"I know I shouldn\'t do this but it\'s oh so convenient.\" questions. Sorry about that.
I plan to use CouchDB for storing a bunch of documents
If you reformulate the sentence a bit, it says: "Any update, regardless how minor can completely change the behavior. We guarantee you can use it for concurrency, but nothing else."
Therefore I would not rely on it because in our industry, stuff like that will haunt you in 6 months, unless you can absolutely guarantee that you never, ever update CouchDB.