Seems to me you missed a few keys from the feature, one of them ( discussed) if a sort of _account_ key what must provide portability between DVR/STB in one account.
You made up the 'USB ports' out of blue.
Well, I'll add to this - PocketDish is the USB External Storage when you connect it to USB post of 622 or other DVR.
And PocketDish's internal disk [HDD] is working now.
I'll pile a little more sh^%$ for you - if I'll install other disk ( up to 80 GB ) into my PD, it will works as old one; so I can use MANY external ( to 622) disks right now.
No way man !
I saw other day in Internet there is USB2 [ACOM ?] external disk enclosure [PATA] , it can substitute PD with any size of hard drive what you can afford .
Depends on what you're recording or moving to that drive (whenever USB connectivity is enabled). With the Voom channels eventually going to mpeg4, recordings of any programming from those channels will take up less space than they do presently.
Given what I'm seeing on my 622, if you are recording off of MPEG4 channels, a 500GB drive would hold somewhere around 150 hours of HD, maybe a bit more.