Many clients have customers who do not have credit lines and only want to ship product if a credit card has been pre-authorized. These orders will initially be placed on Credit Hold systematically, but an approved pre-authorization will act to remove the credit hold from the order.
This creates a problem in situations when the client partially ships the order and back-orders are allowed. The reason it's a problem is because the original pre-authorization is effectively cancelled after a payment is captured during invoicing of the partial shipment. Unfortunately, once a credit hold is lifted from the sales order, it cannot be reactivated unless the value of the order is increased. From a practical perspective, this places the client at risk. If the back order is replanned, there's no safety net to ensure that they get a secondary pre-authorization for the remaining order to guarantee payment.
This is requiring client's manage back-orders in a way that is unsustainable without heavily leveraging GIs and event notifications.