There needs to be more criteria options when creating rules for the Rate Shopper. The most important for us would be to have the rule look at a "Deliver By" date on an order and select the cheapest option that will make it to the customer by the deliver-by date.
An even better option is to say, if there are x days between the ship-by and deliver-by date, select this service/rate shopper rule, which could be executed through the automation rules.