When a user upgrades or downgrades their auto-renewable subscriptions via the "Manage Subscriptions" URL, how is the application notified of this? It doesn't appear that any kind of transaction is processed on the transaction queue, so how is the application supposed to know that something has changed? When does the receipt get updated with this information?
If a user upgrades from subscription A to subscription B, how does the app know this has occurred? If there was an SKPaymentTransaction in the app, we're not seeing it.
Since there is no sandbox support for this scenario, I have no idea how to handle it.