Backing up series links to a USB key would be a good use for that, especially if the external hard drive is an extension, and the series links are still internal.
I'd rather have the series links back up to DirecTV's website (e.g. cloud). Frankly, have the whole receiver profile up there (favorite list, config, etc), and when you swap out a receiver, you just pick one of your profiles to download onto that receiver.
I'd also like to see better use of the internet data path -- as an example, when a receiver is rebooted that has internet connectivity, download the guide via internet and get a picture on screen faster. Could do same for software updates.
Eventually, when you get to all receivers having internet connectivity (5 years down the road?), you could pull all that load off of the satellites.
Update: Whoops, just saw JosephB's post, not sure how I missed it on my first read through. Anyway, seconding what he said.
Edited by jmpfaff, 04 January 2013 - 03:52 PM.