That's a good question Womble, over the weekend I'll sit down and make a comparison by watching the same NTSC discs on both. Really I need to hurry up and rebuild my "A/V workstation" PC, then I could take some screengrabs and post them. In the meantime, slight differences include the D925 having a better laser (transport?) and perhaps error correction. This might be because the technology was made more recently.

I played a disc that has a big crack near the centre on both machines, the 4400 attempted and gave up whilst the D925 was able to cope, albeit with a distorted image. I only did this for a few seconds for fear of damaging both players. The 4400 appears during some scenes to have more ghosting, but again I'll sort out some grabs for you to check out soon.

Transfers? Well, they'd have to include Star Wars, wouldn't they? :)

The U.S CBS/Fox 1989/1990 LD's, I'm not sure if anyone else noticed this but the 1990 ROTJ (which of course is a re-package of the 1986 JPN release) has the full dialogue of Lando in the Falcon which is missing from all the other pre SE releases.

The Phantom Menace JPN LD (tried to locate the theatrical cut at various places online and the best I ever found was a VHS rip with static on the audio and elements of "Macrovision resistance").

PAL SW OT 1997 SE LD box set, which will include all the extras (obviously I'll be using the D925 for this job and will try to get the best results I can).

Criterion editions of Menace II Society and Dead Presidents. The new director's cut of Menace on DVD & Blu-Ray doesn't have even half the extras present on the Criterion LD and the commentaries are different too.

Pioneer WS SE version of Basic Instinct - according to this review the LD's director's commentary and extras are superior to those on the unrated DVD.

There's a few others I'm looking into but I think this lot is more than enough for me to be getting on with for the meantime :)