I haven't used the Edge. It should provide results comparable to the 983H when handling 480i sources (taking into account the central factor of source quality - good/bad DVD transfers, excess compression in cable or satellite broadcasts, and the general limitations of VHS).

I have used the Onkyo 885's Reon scaler with a few sources. One thing I found was that it was difficult to get my Scientific Atlanta to output a "source direct" signal - in fact, it was impossible to output 480i via HDMI, and doing it via component forced me to sacrifice pillarboxing of 4:3 content (something that the 885 couldn't automatically do for me, although the Edge may be more capable in that regard). The 885's Reon also takes a while to lock onto new video resolutions, which irritated my wife so much that I was forced to lock the cable box into a single output resolution (which greatly reduced the opportunities for using the Reon processor). When I was able to get all the stars to align, the Reon did a noticeable better job of deinterlacing than my cable box did, which was nice for watching SD channels.

For HD channels, video processing requirements should be less significant. I believe that the Edge does offer some noise reduction features, which could be useful for HD content (especially when a cable or satellite provider has turned up the compression).