Long time lurker, infrequent poster - figured I'd chime in on my set.
I have a 50GT25, October build date, from Amazon. Have had it 3 weeks - no buzzing, no floating blacks (and I've watched the Dark Knight multiple times to find it). Only complaints are phosphor trailing (which I'm sensitive to and may be getting better, or I may be getting used to it) and inconsistent grayscale - I see red and green push at various levels of the grayscale ramp. I wouldn't mind if it wasn't detectable in regular viewing - cloudy skies and shaded walls/interiors bring it out.
My stock offsets are:
First tried Nutdotnet's settings a week or two ago, and things were slightly improved. Then tried Zodduska's first offsets and they were much better. Now that it's become clear that some sets have high R-drvs stock (like Nutdotnet's) and some have low (like Zodduska's and mine), it makes sense why Zodduska's looked better.
Like Zodduska, I tried today to start at Nutdotnet's stock settings and make his latest adjustments. The variability between red and green throughout the IRE ramp has reduced, and instead has been replaced with consistent red push. Makes sense since R-drv is now well higher than my stock R-drv, while evrything else is in the same ballpark. Will probably try to find a R-drv that works, or wait for Zodduska's latest (and I should say I, like many others, greatly appreciate the efforts of these guys and gas_leak). I of course realize that I really should use a meter, which maybe someday I'll do, but I don't currently have access to one.
One other note, my color setting has consistently needed to be at 52 (about 5 higher than most here), both through my PS3 (as has been previously reported), as well as through my Directv HR24.
Look forward to more settings and getting the set dialed in. Despite the minor issues, it's still an awesome bargain - especially if you get one with flaws you can live with. Do wonder about the high vs. low R-drvs - maybe it's a 50 in vs 46 inch thing?