Personally I've had a look at the Rocket (a friend has it, I've got the HDPVR 2 Gaming Edition).. It seems pretty cool, you can have live game commentary and stuff or you can add it with the software like the HDPVR I have.. it's got a 4MBPS higher recording rate than the HDPVR 2.. but the thumbdrive idea isn't amazing.. you need something like a 16GB-32GB thumb drive to really take advantage of it, I mean these don't cost too much but you can't plug a 500GB-1TB External HD into it which would probably be cheaper and it would hold more..
Overall they're pretty cool and rather impressive, excellent video quality and a great idea with the live com feature.. will be great for taking to events and such as you don't need to take a laptop or anything and you can just plug in the headsets they provide to give a live commentary at the event for uploading later. If I get bigger one day and get invited to live events for releases and previews I might invest in one