Just got done with playing around with my PN50C8000, a few initial impressions for the curious:
PQ is great out of the box. Made a few tweaks using the Spears and Munsil disk, but not much. Using CAL-DAY mode.
Motion resolution is awesome which is what I really wanted; my A550 would smear and judder the crap out of everything. Cinema Smooth does brighten the picture but not by anything too noticeable I can see at this time. MJC does not, but it has the weird "3D" effect and you can't use it and CS at the same time. Going to have to play with this and make a decision.
3D is fun, but it does have some ghosting and IR. I understand there's a firmware update out there for this but the TV doesn't want to get on the internet- can anyone get me a link?
It does have a bit of IR, but not bad. You can generally only see it when you're right up on the screen. It disappears super fast, generally speaking, as well.
The only time mine buzzes is if you stick your head right next to the back of the screen, and you can't watch movies like that
...Now for the confirmation everybody's been waiting for.
Black levels are pretty good out of the box, roughly half what my old A550 LCD had. Note that I haven't had a chance to check it out in a fully black room yet.
Additionally, I can confirm what Spanbauer said about the black levels. There's some sort of "full screen IR" that happens. The reason I was able to pick up on it was because I was watching a movie that was a little wider than 16:9 and after watching for a while the center part of the screen got noticeably (about 2X) brighter after a while. I turned it off and lowered the contrast down from the standard 90 in movie mode to about 65, let the TV cool off and retested and it's much better although it still does it a little.
...I'd guess it probably goes away as the TV breaks in provided you don't leave it in super torch mode all the time.
All in all, 100% happy with the upgrade so far.