I would go so far as to "bypass" the spec of CouchDB -- at least for Pouch -- by doing a sort of auto-compaction, clearing out the database of the previous revision at storage time, and only storing the latest revision. This doesn't stop you from doing an effective merge, it simply stops the original notion of Couch having multiple branches of the same document. Again, in the browser, to sacrifice indexedDB space, I think that's an okay step to take.

The real win will be when a WebWorker is able to run through a view and automatically add the results of that to a separate dbspace. It looks like viewQuery is the beginnings of that.