I am typically going to use this to record from hi-def video conferencing systems such as the Polycom HDX9004 which puts out a 720p HD signal so you can record all of the people, PIP, even computer content that was part of the conference in HD. Then play it back as required i future class and perhaps even archive it to there servers.
I did not go to the HDTV recorder section as there will never actualy be any HDTV recorded.
Click #1 in my signature for two SDTV DVDRs with HDD that might be ideal for your purposes? They'll downrez the 720p to 480i which is reqd for recording in a SDTV unit. They can uprez the recording to 720p or 1080p if desired for playback, but obviously it'll still be an SDTV source... might be OK for your purposes.