Putting everything in one group and requiring it to be first is useful, and also adds consistency to head-in-entry, as evidenced by the introduction of the feeder element. Also "feeder" is a horrible word.
And "head" doesn't suck? I struggle to type a sentence on the subject without making an unintentional pun. "source-feed" is fine. The section on atom:head is totally confusing and bad--it's easier if you just do it the way PubSub does it *right now*.