Your UPS rates are GREAT, and I would love to use Ship for that reason, but I need a couple of functions to be added to Ship before it would make sense for me to use it... See below:
Single Shipments: See Stamps.com online single shipment window: you can enter all address info, select shipping option and add-ons, and print the label all in one window. Rates are updated in real time as you select different rates/add-ons and change ship-from/ship-to zip codes. It's very easy to process a shipment.
Batch Shipments: If I need to process 500 shipments at once, I need a way to upload a spreadsheet file. Ask your shipping department about this; I'm sure they do it everyday with UPS WorldShip or a similar application. It would be impossible to process all of the orders manually, so there needs to be a way to add all of the shipment data into a spreadsheet and upload that to be processed.