This is not really a problem, more like a general X vs. Y question.
So I'm experimenting with c2dm on android using a server written in google app engine. At the moment I'm using the "App Engine Connected Android Project" as a template with some added code myself. So the generated code use RequestFactory for a bunch of stuff, like registering/unregistering devices, sending messages, etc.
My previous experiences with backend communication has existed of setting up a connection to a servlet, writing to it (json) and reading the response (json).
So here's the question: What are the benefits (if any) with using the RequestFactory for communication with the app engine instead of just writing/reading from an URLConnection's input/outputstreams? Or is it really just a matter of taste?