Why waste the space when you've only got at most an 800x480 matrix?
Are you purposely missing the point?
PD's only work with these USB receivers: The 522, 622, and the 722 (so far). The 522 is SD only so everything you record can be sent to the PD but it is USB1.1 so it takes ~40 minutes to transfer an hour of TV. And it won't make HD recordings for big flat panels.
The receivers that work best are the 622 and 722 USB 2.0 receivers that can transfer an hour of SD TV in ~8 minutes. the PD works GREAT with these receivers.
But, now follow me closely here harshness, they are HD recievers that 99.9999% of the world uses to record, when possible, HD versions of TV programs for big flat HDTV screens. This includes me. And day by day more and more of my shows are available in HD.
Now stay with me here. THESE HD RECORDINGS CAN"T BE CHANGED TO SD TO BE PUT ON THE PD. NOR CAN THEY BE SENT AS THEY ARE TO THE PD.
THERE FOR, PRACTICALLY NONE of the shows I record to watch at another time can travel with me in my PD.
No one. No one. I say again, no one gives a rat's ass about the resolution of the PD screen or the resolution of the recordings that are kept on the PD.
If resolution is that important to you when you travel, every town with a population over 1,000 has at least one bar with 40" or larger plasma TVs that show HD pictures from opening till closing. And for a few bucks more that Motel 6 charges for a room a growing number of hotels have rooms that have good sized HDTVs that will let you watch pretty HD pictures anytime you travel.
For myself, I want to watch the shows I record and Dish has made the PD into a cruel joke for most of us. This is not to say it is not a cool gadget. It's just mostly useless to most folks most of the time. And grows more so every day.
But this misery could all be ended if Dish made a receiver or PD that could convert these HD recordings to SD so they can be taken on the road, or camping or whatever.
The resolution of a 7 or less inch screen is irrelevant.