Hi Mike Austin,
Having two progress areas is the better solution. You can choose which progress area to be visible and which one - not in the client-side OnClientProgressUpdating
event of the progress manager.
Custom data can be added to the Progress context, it can be retrieved through the args.get_progressData() method.
the Telerik team
Check out Telerik Trainer
, the state of the art learning tool for Telerik products.