I had a chance to look at a D7000 next to a GT30 at Magnolia the other day, which has answered some of my questions. Others have been answered here (thanks!). Here's the current state:
1) RBF: The image starts to darken at about 45 degrees vertically, but never goes completely black. It's very much like some computer LCDs dim from side to side (no apparent color skew, just darkening). RBF, in contrast, has no effect side to side. It shouldn't be a problem for my viewing setup.
On the other hand, I couldn't really tell whether the reflections of overhead light were appreciably dimmed, but they didn't seem any worse than the GT30, whose reflections had rainbow lens-flare-like streaks. So I don't know whether it'll do a whole lot to help with the reflections in my environment.
It didn't seem any worse than other reflective displays I've seen. Out of curiosity, how "matte" is the D6500?
2) Peeling: no reports of problems on the 51"
3) Line bleeding: this seems to be universally confirmed, but generally not visible on normal content
4) Image retention: temporary IR seems to be real, especially early on and with the brightness dialed up. Some people claim that it doesn't happen on their screens, but that may be due to conservative calibration and reduced brightness (totally fine, by the way).
Unresolved:How is Samsung's record on fixing problems?
The comments I've seen suggest people are pessimistic. (6) and (7) below especially seem like they'd be fixable via firmware.
5) Permanent burn-in: are D7000s susceptible to permanent burn-in (more so than Panasonic)? Does the Samsung screensaver activate reliably?
6) FBr/brightness pops: This isn't just normal ABL, it's very sudden noticeable changes in brightness (perhaps related to ABL). 2011 Panasonics have had issues with this, but apparently there's now a fix. Some Samsung sets seem to have it, some don't. Does it affect the 51" displays?
7) Inability to turn off DNR: Here's the review
that discovered it. Is there a fix for this in the works?
8) Color banding (not line bleeding -- see this post for a sample
): I've seen a few reports of this, but they've been fairly few. Is this a real issue, or has it simply been due to overly compressed sources?