Here, why spend $400 on an Oppo when you can just spend $135 on a Denon:
http://www.ecost.com/Detail.aspx?edp=35126367
Specs aside, I bet you cannot even tell the difference in either video or audio performance between the flagship Oppo and this lower end Denon DVD-1930CI.
But, of course, you are free to disagree with me.
Given that I am using the HDMI for both audio and video, I expect I would not hear a difference between them. However, from seeing the Oppo in action, I expect I would see a difference. To get some idea of some real world improvements in picture that are clear to see, take a look at:
http://hometheater.about.com/od/dvdproductreviews/ig/OPPO-DV-983H-HQV-Test-Results/
To keep us from having a discussion that is too unfocused, look at:
http://hometheater.about.com/od/dvdproductreviews/ig/OPPO-DV-983H-HQV-Test-Results/OPPO-DV-983H-Moire.htm
Compare with:
http://z.about.com/d/hometheater/1/0/D/Z/racecarmoireexmaple.jpg
This kind of thing is fairly common on DVDs, and whether one's player deals with such things well or not will be very easy to see. Of course, it is not every moment of every disc that such things will be present, but it is easy to see when it isn't right. For examples of other things that can show up and look bad, take a look at the first link in this post and read all of the pages of the article, looking at the pictures and examples as you go.
With the high end Oppo, they send a test disc with such things on it. I tried it out on the new Oppo, and compared with my old player, which passed some of the Moire tests, but failed others. When it fails, it looks like crap. The new Oppo makes a difference, sometimes dramatic, sometimes not very noticeable. (I have another test disc that has things that look much better on the new player, so it isn't simply a matter of making a disc that specifically makes the Oppo look better.)
Now, how well that Denon would deal with such things is something I don't know, but it is doubtful if it could deal with them as well as the new Oppo.
I want to try to be perfectly clear about something, since this discussion seems to be rubbing you the wrong way. I don't think you are recommending bad players. Denon, as I have already said, has a longstanding reputation for making excellent DVD players. But I am saying that they are not the best value. And that makes them not a good buy, and not a good recommendation.
Judging from the reviews on line, the Denon DVD-5910, when it was originally released, was probably the best DVD player available at the time. It was, however, quite expensive. Now, judging from the reviews on line, the Oppo DV-983H is probably the best DVD player ever made. If that is so, then there is no reason to spend more than $400 (excluding shipping) on a DVD player. And if one wants to spend less, the lessor Oppos are also supposed to be a great value. The Oppo DV-981HD is supposed to be extremely good, and if Oppo had not released something better, it is what I would have purchased earlier this year. (The Oppo DV-980H, with its significantly inferior PAL to NTSC/upconversion performance, would not suit my needs, so it was never a consideration for me. For those with only NTSC DVDs, such considerations are irrelevant.)
Frankly, when one considers that the video processor in the Oppo DV-983H, when purchased as a DVDO video processor, costs literally thousands of dollars, it is amazing that the Oppo DV-983H is only $400. I would rather have the Oppo DV-980H and the appropriate DVDO processor, so that I could also send other video sources through it, but it just isn't worth a couple of extra thousand dollars to me for it.
