Comparing the two 65s, the Sony is definitely the superior set. That XBR is a full-array LED set with local dimming, the Samsung D8000 is edge-lit LED with ineffective pseudo-local dimming. As such it will have generally weaker black levels and more backlight distribution issues than the Sony.
As far as the motion handling, I don't think anybody really knows for sure what exactly Samsung's "Clear Motion Rate" numbers (480, 600, 720, 960 on the D8K) or Sony's MotionFlow ratings (XR240, XR480, XR960 on the HX929) are meant to represent. Neither company manufactures sets that have an actual refresh rate that exceeds 240Hz, but they're probably factoring in backlight scanning/strobing + black frame insertion systems to arrive at higher "perceived" refresh rates, hence the higher numbers...mostly marketing speak to pander to "spec sheet" buyers. Same for contrast ratio; the numbers mean nothing here.
ht Panasonic 60" ZT60, Monitor Audio: Silver RX6, RX Centre, RX1; Martinlogan Dynamo 700, Marantz SR5006, PS3, Oppo BDP-103D, Panamax M-5100PM
2ch Sony 32" W650A, Sonus faber Toy Monitor, REL T3, Marantz PM8004, Sony BDP-S1000ES, JVC T-X3 tuner, Apple TV, Peachtree Audio DAC•iT, Panamax MR4300
pc Monitor Audio Radius 90HD, Audioengine D1, FiiO A1
+ Sony 65" XBRX850B, Sony BDP-S5100