Switchable Billing Tables / Alternative Rate Tables

The general idea is to add an option to setup a secondary rate table that could switch an entire system to the alternative rates. An example would be a rate table for standard rates and a rate table that is used in times of emergency. Currently you have to update the rates to reflect such a change, however you would naturally update it back when the standard rates would reapply. Setting customer accounts specially can be a small work around, however this can lead to human error causing billing issues or be highly time consuming to update multiple accounts. Simply put, I suggest system feature that would allow 2 rate tables to be setup and an option to switch the system rates to the alternative rate table and back when desired.