Oops. I just read on Bang-olufsen.com about the new sets and according to specs it is like this now:
55”: Ultra High-Definition (4K), direct-type LED panel with global backlight dimming
75”: Ultra High-Definition (4K), direct type LED panel with global backlight dimming
85”: Ultra High-Definition (4K), direct type LED panel with 2D local backlight dimming
I don 't think "global" is a good thing. It would mean that there is no zones dimming individually at all, instead that the entire screen is dimming as one big element(!). If this is true, then actually the old Avant is better than the new one in the case of backlight. I am not sure this is the case but a quick googling gave me this:
Global dimming One last trick isn't really "local" dimming as much as it's just "dimming," or maybe "global dimming." The entire image will get darker with dark scenes, and stay bright with bright scenes. On many models when given a full black image (like the fade-out at the end of a movie, but before the credits start) the LEDs will shut off completely, making it seem like the TV has a really good black level.
Global dimming One last trick isn't really "local" dimming as much as it's just "dimming," or maybe "global dimming." The entire image will get darker with dark scenes, and stay bright with bright scenes. On many models when given a full black image (like the fade-out at the end of a movie, but before the credits start) the LEDs will shut off completely, making it seem like the TV has a really good black level.
This is fake, of course, as you can't see anything else on the screen. If anything should appear, the LEDs kick back on, and the black level jumps up, revealing the TV's true contrast ratio. There are some tiny energy-saving benefits to turning off the LEDs, but visually this is distracting. It's also really common among projectors (where an auto-iris tracks the incoming signal).
Another variation of the theme senses the average brightness of the scene and, during darker scenes, ratchets down the whole backlight. Again black levels improve at the expense of highlights and sometimes-visible fluctuations in overall brightness.