Re: "His misinformation is this: XMPP is XML based. The bandwidth that Google most likely refers to is a result of verbosity of XML. You can't eliminate that by extending XMPP, something that a guy who serves on XMPP Council should know."

He directly addresses the Bandwidth concern by noting that interoperability on the server side is irrelevant to mobile anyways:

"Of course none of these concerns for mobile are applicable for server federation. As far as I know, the Google Talk client on Android doesn't even use XMPP as the client-to-server protocol."