Hard drive based DVD recorders generally have several advantages over DVD-only recorders in that you don’t need to always have a disc handy for recording and that you can do a lot more editing to recordings before transferring them to DVD. For example, the LVW-5045 I have lets me split & merge recordings, record programmes longer than the capacity of a DVD for a given quality (which can be split across DVDs later) as well as transfer recordings to more than one DVD such as if the DVD I used was faulty or of poor quality. Finally, most HDD+DVD recorders allow time-shifting, in which you can view the TV, satellite, cable, etc through the recorder and be able to pause it, rewind over scenes, etc.
I would imagine that jitter would be a lot less than with DVD recorders since they generally transfer recordings from HDD to DVD at the writer’s maximum speed or what the disc is capable of. When a DVD recorder records directly to disc, the DVD writer has to keep starting & stopping since the writer has a fixed writing speed throughout the disc (usually 2x to 8x depending on the writer and disc), where as a live broadcast, particularly one recorded in a longer play is between 1/6x and 1x, which means that the recorder has to buffer up some recording, write this buffer to disc and then repeat this step continuously until the recording is finished.
So far, I’ve been happy with my Lite-On HDD+DVD LVW-5045 and the quality of the recorded discs (DVD+R & DVD-R) are generally on par with that written in a PC LiteOn DVD writer (see the disc quality section of my review).