The range of possible modulation in the backlight is directly proportional to the peak brightness - the dimmer or more "standard" you set the peak, the less it can spatially modulate the backlight unless severe compromises in image quality are accepted (eg, extreme intra-frame floating whites). This is a function of the optics and independent of the number of individually controllable zones.
At "standard" brightnesses, the halos should be more or less the same as with the latest Sony/Samsung models - the increase in control density is offset by the increase in effective cluster size necessary to get light where it needs to go. At high brightness the halos won't matter much, of course, as you're more or less intentionally blinding your eye.
The display will almost certainly look good, as do the current Sony/Sammies, with the added kicker of high brightness. Two-thumbs-up of greatness on the brightness, as it should look terrific in ambient/daylight-like viewing conditions.
XRox - Sony, Samsung and Sharp all have published patents on per-pixel LCD compensation with backlights of this kind, and there is no reason to believe their current offerings don't implement the technology.