I have both a 65" V10 and a 46" PZ80U and neither seems to be affected by the rise in black levels. Or if they did, it is not noticeable. The PZ80U has 2500+ hours and the V10 has 1200+ hours on it. Picture is still great on both of them and yet to see a drastic change in black levels. Maybe a little rise but barely noticeable and still better than most sets ive seen besides Kuro's.
Ive also left static images on my PZ80U for 8+ hours before on 25+ occasions and never had any image retained for more than 5-10 minutes. Its been a pretty solid set for me.