Ok, before we get hopelessly confused, which is not very hard on an Airbus, what is this talk about half deflection being available with autopilot on? All it says in my (edit: A319) books is that you get half rate when flying faster than .75/315 with AP engaged. No more, no less.
The part about anti-ice, with airbus one must be always very suspect of translation vagueries (French to English). I know, a dangerous statement, but not less true.