The actual black levels are good, deep, and inky since the backlight and algorithm are good. The issues pop up when there's some small bright areas next or mixed with really dark areas...in the form of halos due to the limited number of dimming zones. Sony prefers to maintain correct picture Brightness and therefore might show more blooming while Samsung dims the picture to show less blooming.
It's not as bad as videophiles on forums make it out to be, and in general you will be really happy with 85".
Sony XBR-77A9G / Panasonic DP-UB9000 / Marantz SR7011 / Def Tech 9060 Series