We're just back from Poly - and yes we received a magical upgrade!
We had booked GV concierge for our first night and GV for the next 6 nights. When we arrived at check-in the CM said "you're room is ready (it was 11am so I was already happy with that!) - just hold on a minute. You won't need to switch rooms tomorrow - I've changed your reservation to keep you here for the balance of your stay" He did it on the spot - without us asking. He told us that the changes are usually done randomly in the back room of the main desk. The poly allows the GV rooms to overbook and then the extra reservations are moved thoughout the resort - sometimes better view -sometimes to concierge.