The problem with hard drive recorders is that they encode to MPG2 'on the fly'. So a video encoded at 5.5 Mbps through your video camera will never look at good as a video encoded at 5.5 Mbps on a PC (3-4 passes VBR).
Personally, I'd run at 8.5 Mbps on the camera - this will allow you to fit about 60 minutes on a DVD5. But don't be tempted to re-encode your footage to fit more on a disc.
Also, will you be synching up a PCM audio track with your video? If you're using the 8.5 Mbps setting on your camera, make sure that the video + audio bitrate doesn't exceed the DVD spec when you add in your PCM track.
Hope this helps.