Sure!  Just a few things I'm noticing while testing the behavior of recommended api. 

I see here  that if opts.complete is undefined it is set to the callback (which in new api is undefined): https://github.com/daleharvey/pouchdb/blob/master/src/pouch.replicate.js#L248

Problem I'm having is if callback is undefined then the complete function is not run for some reason.  here's the logic that's working for me so far:
https://gist.github.com/tahmmee/6001820