As a DISH Network dealer I would be in favor of a DISH Branded Drive, and have the DVR's software written only to accecpt DISH branded external drives.
I think the drives should be available for purchase through a local retailer, in addition there should be a rental option available through DISH.
Instead of USB, I think they should have Eithernet Drives and utilize the Eithernet port on the back of the receivers so the hard drive can be located in another room away from the receiver.
Finally, they should write software for the 211 so it will accecpt an external drive so if the customer wanted to upgrade to DVR all they would need is a new remote control and an external drive!