Rob,
I had always owned Pioneer DVD players, mostly because I started in this hobby about 12 years ago with a Pioneer LD player. I got the DV-45A because it was about the cheapest universal player around and I wanted to try DVD-A and SACD. I enjoyed what I heard, and could live with the picture, even though I knew that it wasn't giving me top-notch deinterlacing. Then I got an Pannie RP82 and the differences were apparent. I'm not saying that the Pioneer looked like an old VHS tape in comparison, but I noticed several little anomalies that I had always just accepted with the Pioneer simply weren't there with the Pannie. I think what I really noticed more than anything was the absence of combing. Anyway, that sold me on the Pannie for DVD viewing.
When the Denon 2900 came out my friend at the A/V store offered to let me take it home and see how I liked it. Well, it never went back. The build quality is far and away the best I've ever had in a DVD player, much better than the DV-45A and better than my prior DV-37. It reminds me more of my LD players. Anyway, the picture quality of the 2900 is comparable to the RP82, and probably I like it even better. Can't really articulate why, and I only have one duplicate DVD for A/B testing, but the picture just seems better to me. Add in that I like the remote better, and there is no layer change, and the Denon is preferred.
With audio, I also found that I preferred the Denon. My suspicion is that it is doing bass management better (or maybe, it is doing bass management), so it just sounds better to me. More full, more real. Perhaps I just have it set at a higher volume. Anyway, the DV-45A got shuffled off to the bedroom, and is now with me in a second system in my girlfriend, er, now wife's, apartment. I still like it, but given the choices, I would never buy it again when I could get pretty much the same thing for less in one of the Pioneer budget players. But I probably wouldn't go that route either now that I've seen what good deinterlacing looks like. Whether Faroudja or SI, any future DVD player will have to have something comparable. I think the Denon 2200 looks like a good package based on the specs. It might be the way to go if somebody doesn't want to spring for the Denon 2900.
