Thank you for the information, as there are several vendors to choose from I will either get an WD or Hitachi - both seem adequate and well priced. I am not too concerned with the hard dive throughput rates because both it looks like can handle video throughput even at 1080p.
I was/am concerned a little bit with saving two channels video with the DVR and watching a third all at 1080p. I do assume that the DVR will optimize the drive just as it optimizes the internal drive now at nights. However, if the drives are truly running at Sata III even at 5400rpm I suspect it should be able to keep up. If you feel different please response. I looked for such a subject (throughput on dvr with three 1080p streams going) but didnt find one.
I did find this drive which looks perfect and made for the task but not for sale yet? Hitachi CinemaStar 5K2000
For those still looking at this topic - I STILL would like to find external power enclosures with spin down - especially for those tasks that need the speed (my normal computing day) rather than slower green drives.