I received my LX6090 2 days ago. Out of the box I disabled all picture enhancement options (ACL, DRE, etc.), set other picture options to neutral, and tested it with a blu-ray disc (I Am Legend) in a completely darkened room. The contrast and absolute black level are certainly at a new level compared to the 8g Kuro's, which I have seen in similar conditions.
When the set displays just a black image, you can still see some luminance if you allow your eyes to adjust. However, when there is any picture on screen my eyes experience the black areas as completely black. The contrast is simply amazing in a darkened room. Daytime TV is a different story though, but that is not unexpected and not really an issue to me.
Overall image quality is stunning when watching blu-ray. It is as perfect as we have come to expect from 8g Kuro, with the better contrast and black levels for an even greater experience.
There is some plasma buzzing, but it quickly dissolves into the sound of the movie, and into your subconscious.
Also amazing is the SD PAL image quality. From a 6 ft viewing distance is is still watchable. I had not expected that on a 60" display.