I posted my full review of the WD-65831 last night on the general 2007 Mits DLP thread, but since there are apparently some who only follow this thread, I will repost my comments here:
I've had my WD-65831 10+ days now, and am now ready to share my detailed evaluation. Actually, I was ready a few days ago, but just haven't had the time to write it up until this evening (Pacific Time.)
Background: I purchased a Sony KDS-R60XBR1 in late June 2006. Due to a green blob problem that quickly developed, Magnolia swapped it out for a KDS-60A2000 in mid-August. Originally, I had thought to swap the A2000 for a R60XBR2, but decided to get a WD-65831 for the following reasons: 1) The new XBR2s don't support firewire, 2) the 65831s would be available from Magnolia several weeks before the R60XBR2, 3) the larger screen size of the 65831 (with no significant price difference,) 4) fear of the green blob (which also began to show up on the A2000,) and 5) my opinion, after auditioning a 65732, that it was overall quite comparable in PQ to an A2000.
If you're looking for a comparison against the new RxxXBR2s, you'll have to look elsewhere: I haven't seen any RxxXBR2s yet.
Executive Summary: The 831s are not perfect, but they are excellent televisions. In most cases, they meet or exceed the performance of any competing microdisplay-based TV I have seen, although they don't win every contest over every performance parameter against all competitors.
There are other microdisplay-based TVs I would also strongly recommend, especially Sony's SXRDs. As Westa6969 says, I am haunted by the picture of the Sony SXRD sets (and also a little spooked by the Green Blob). However, I would be just as haunted by the picture of the 831, were I to go back to an SXRD. What I really want is a TV that combines the best of both. Unfortunately, such a thing is not for sale, so...
As to whether or not the screens on the 831 and 732 are the same, I have no idea. I also couldn't say whether or not Mitsubishi changed screens from one production run to the next.
The screen on my set is an anti-glare screen, with a matte finish. Although it reduces glare and reflections quite well, it's not perfect. You can see reflections in it, although they are quite dim and muffled. When the TV is on, it is much harder to see any reflections or glare, although they can still be seen in the right conditions. The screen is noticeably more effective at minimizing glare and reflections than either of the SXRD sets I had previously.
You can see SSE. Specifically, you can see the graininess of the screen, although whether it can be seen, and to what extent, varies with the picture being shown. SSE tends to be more visible in lighter areas of the picture, and when the camera is panning. It tends to be less visible when the camera is still, and/or when the picture is dark. SSE becomes essentially invisible once the viewer moves more than about 14 feet away from the screen (of the 65" model.) I happen to sit about 12 feet away from mine.
The image presented by the 831 strongly resembles what one would typically see when watching a film projected onto a high-gain, grainy screen. Compared to the SXRD's picture, it's grainy.
The picture is unusually sharp. One reason for that is the lack of any misconvergence. In my opinion, this is the major reason the DLP-based sets appear sharper than the LCoS-based sets do, even among sets that are all natively 1080p.
Another reason that DLPs (such as the 2007 Mitsubishis) appear sharper than the LCoS-based microdisplays is for the same reason that the direct-view plasma and LCD sets do: the greater separation between pixels. Of course, the greater separation between pixels also causes SDE--although you won't directly see any SDE unless you are way too close to the screen. At any reasonable viewing distance, you see no SDE at all, but the picture appears to be sharper than it does on the LCoS-based sets.
On the other hand, the smaller inter-pixel separation of the LCoS-based sets provides a greater pixel fill factor. Although that makes the picture look blurred and/or smooth (as does the misconvergence between the three LCoS chips,) it also gives the picture a more liquid look.
So it's a tradeoff: Liqudity and smoothness versus the dry, grainy look. Or the sharp, photograhic look versus the blurred, fuzzy look. There are times you'll think the first characterization is more apt, and times when you'll think the second is a better fit.
In fact, a good way to describe the difference between the 731/732/831 and the SXRD sets is to compare it to the difference between a photograph printed on grainy photographic paper versus one produced by the Polaroid cameras in common use 20 years ago that had a glossy surface.
What I'd like would be to have the sharpness/clarity of the one, and the liquidity of the other, without any blurriness, and without any unnatural sharpness. Unfortunately, I know of no such set available for sale at any reasonable price.
Black levels: The 831 has best-of-breed black levels--superior to that of any other microdisplay-based set I've yet seen. In just about any situation other than a totally dark room, the blacks are inky. Even in total darkness, the blacks are a very dark gray--at least as dark as they would be in a typical movie theater. The SXRD sets aren't quite that good.
Dark picture detail: The 831 has best-of-breed dark picture detail--superior to that of any other microdisplay-based set I've yet auditioned. However, there is a very fine line between black crush and picture fogginess, and no one setting of the brightness level hits that sweet spot for all picture content and/or for all amounts of ambient light. Sometimes, you can find the sweet spot where there is neither black crush nor fog, and other times you can't. But the sweet spot where neither flaw is evident seems more likely to exist with this TV than would be case for other TVs. Even when there is no sweet spot where neither flaw is evident, any black crush or fog can usually be made to be quite minimal.
Depth: Thanks to its great black levels and dark picture detail, the 831 can present a stunning sense of depth. In fact, this is where I experience the greatest WOW-factor with this TV, even compared to the SXRDs (which is quite an accomplishment, by the way.)
However, the SXRD sets do sometimes produce a more compelling sense of depth, for two reasons: 1) The less grainy, more liquid look of the SXRDs sometimes gives objects a more 3D, depthy look, and 2) the polarized screen of the Sony sets also adds depth, although it also makes the picture look dim and strangely-tinted, as though one were wearing polarized sunglasses.
But the more 3D look of the SXRD tends to apply to relatively small objects that don't occupy that much of the screen. When viewing a room, the 831 provides a greater 3D effect for the room as a whole. But when viewing bric-a-brac on a table or shelf, the SXRD sets will tend to give such items a more 3D look.
Color: To my eye, the 731, 732 and 831 provide very pleasing colors. However, the bad news is that the nearest color temperature to 6500K provided by the factory settings is too low by about 1000K. And according to the measurements posted by ISF callibrator Jeff Meier, the color decoding as shipped by the factory is more than a little out of whack. The good news is that, at least for the 732s and 831s, a professional ISF calibrator can use the PerfectTint control to greatly improve the set's color accuracy.
Scaling, Deinterlacing, Inverse Telecine: The 831 does a terrific job scaling 720p to 1080p. It is reasonably good at deinterlacing 1080i to 1080p, and at doing inverse telecine from film-based content (conversion of the frame rate from 24 fps to 60 fps.) It mostly matches the performance of an A2000 for scaling, deinterlacing and inverse telecine--except that it is much better at scaling 720p to 1080p. It matches the performance of my Marantz DV9600 DVD player at upconverting DVDs to 1080p.
Noise, artifacts: There is a downside to the 831's sharpness and clarity: It makes any noise and artifacts painfully apparent. There's no place to hide for any flaws or defects in the original program. Any loss of resolution caused by compression (satellite, cable,) or caused by bitrate limitations (bandwidth constriction,) will be fully revealed.
If the bitrate necessary to transmit the picture at full resolution exceeds the available bandwith (which will happen when watching a compressed signal when the camera does a fast pan over the grass on the football field, for example,) then the picture will blur, the blades of grass will disappear into a green fuzz, and the sharpness of the set will make the loss of resolution quite obvious.
The set's noise reduction filter often doesn't seem to do much. But that's deceptive. What it actually does is to smooth out the picture. For HD content, using the low setting may actually help make mosquito noise less visible, abeit at the cost of some fine picture detail. But for SD, it's effect is far less subtle, and far less desirable.
Standard Def: The SharpEdge feature artificially sharpens the picture. For HD, it's just not needed (it's already quite sharp enough.) For SD, however, it provides a significant improvement. SD picture quality without using SharpEdge is comparable to that of the A2000. With SharpEdge, it's better than that of the A2000.
Rainbows: I have seen no rainbows. But, I've never seen them on any DLP, so that may not mean much. A friend of mine who sees rainbows easily said he also sees them on my 831, but that they seem much less noticeable or bothersome than would typically be the case.
Fan noise: I would only hear it if the sound were turned off, I got within about 4 feet of the set, and focused on hearing it. Otherwise, I don't hear it.
Conclusion: I have mixed emotions. I really like the SXRDs. I really like the 831. I am concerned about the Green Blob. I really want firewire. I have the option to exchange my 831 for an XBR2. So I will audition an XBR2, and think it over. There are many factors to consider, and those who are considering both sets may have a hard time making a final decision that they won't find themselves second guessing later on.