the only UHD tv that was around when I bought mine was the sony with the huge honking speakers on the side. even if it weren't for those speakers, I knew after about 2mins of watching that the sony was nothing special. higher resolution can't fix poor uniformity, poor viewing angles, or poor black levels.
obviously a UHD tv is better than a 1080p tv, but I would also say it's obvious that a plasma tv is better than an edgelit LED tv. the only UHD tv I would ever consider would be an oled, and you won't be getting one for the same price as the f8500 anytime soon.
think of it this way, would you rather have a $30,000 Honda, or a $30,000 Ferrari. Before you answer too quickly, think about what 30k will get you at Honda, and compare that to how many corners Ferrari would have to cut to give you something for the same price.
point is, buying a UHD tv at the same price point as the f8500, doesn't mean it's the same quality. in fact it pretty much guarantees the UHD is of extremely low quality
Displays: Samsung PN64F8500/JVC X35
AVR: Pioneer VSX-1130K, 7.1/5.1.2 audio
Sources: HTPC(Enby), PS3, XBOX360, Wii
Control: Harmony One