I had the 64F8500 paired right next to a 65VT60 in my living room for about a week doing dark room viewing as that consists of most of my viewing.
Prior to doing this, I had actually been strongly favoring the F8500 over the VT60. In fact, I had bought the F8500 first and planned to be done with it all. However, as I reported in the F8500, that first night I had the set I immediately started seeing what I would now call severe floating black on Star Trek: The Original Series - Season 1. These are 4:3 in AR and the vertical "black" bars were changing in brightness very consistently from almost scene to scene - and sometimes within the same scene. At the same time, it was evident the image was losing contrast as well when this was happening. It was puzzling at first because these scenes on my Panasonic 65ST30 were stable and showed a bit better blacks and contrast than the F8500 in some scenes because it lacked the floating blacks on the Samsung. It was really puzzling.
At this point, I started looking at other various Blu-rays including letterbox 2:35 AR material. Once again, I was seeing this floating black issue on the F8500. At this point, I immediately had my doubts about the F8500 and ordered the 65VT60. I spent more hours than I want to admit watching and comparing these displays side by side with various Blu-ray feeds each night. I didn't have a meter, so I wasn't able to calibrate and accurately compare for things such as overall color reproduction (left anything color related to default in the F8500 in Movie mode, VT60 in THX Cinema), but did set brightness and set contrast so that both sets were putting out similar light output and were at proper black level. I used a couple of eye ball techniques for light output which also correlated to what was being reported to achieve close to 35ftl on both displays with particular settings such as Movie mode on the F8500 and THX Cinema on the VT60. So, at the end of the day, these two sets were putting out practically the same amount of light (~35 ftl). I was using an Oppo 103 feeding both players the same feed for each comparison.
Immediately, it became evident the VT60 had notably more stable blacks and deeper blacks. I mean blacks were just rock solid and very deep on the VT60. I looked at those Star Trek scenes again as well as other various movies (which included Sin City, The Dark Knight Rises, Star Wars, Castaway, and others including some brighter material). I would say only about 10% of the time were the F8500 blacks able to come very close to the VT60 and that was on a practically all black screen. As soon as ANY sort of light starts coming into the image from the content, the VT60 black superiority became evident. Sometimes it was subtle, sometimes moderate, sometimes strongly. Even my girlfriend - who is not a video enthusiast as you would guess - was able to see the often dramatic comparisons without me having to point it out. And, maybe more important, the image looks more contrasted on the VT60 as a result - it's not just the annoyance of fluctuating black bars - but a loss on contrast on the F8500. The VT60 will take on a more contrasted image in most scenes. You don't need a meter to prove it (although it will). It will be very evident watching.
Once you understand what floating blacks are and have a very critical eye watching in a dark environment, the floating blacks will be VERY evident. They will also probably be bothersome. I've had several F8500 owners PM me and have since returned the F8500 because of this. Also, we all had the latest firmware update. Let this be clear: the update that addressed the brightness pops DOES NOT FIX THE FLOATING BLACKS. MISINFORMATION IS BEING STATED ABOUT THIS POTENTIALLY CAUSING SOME PEOPLE TO MAKE A PURCHASE MISTAKE. THEY STILL EXIST AS MY EYES AND DATA INDICATED.
One other aspect of these displays is ABL. It is recognized the F8500 has better or less ABL andI would agree with this. However, even in a very bright movie such as Castaway, I only saw a couple of scenes where the sky and clouds looked just a bit dimmer on the VT60 in comparison to the F8500. I viewed a couple of hockey clips and the ice did look a bit dimmer on the VT60. I viewed all of the clips on the Spears disc - some of which a very bright, but no difference there. Some of this ABL effect will annoy some, but I personally found it not to be an issue and FAR less of an issue compared to the floating blacks. I'm sure the floating blacks will not be an issue to some and depending on the room environment.
On any rate, the F8500 is still a very good set and if you need the brightness or less reflection for a lot of bright room viewing, it's a no-brainer. It gets BRIGHT.
However, I find the nearly 41 ftl on my VT60 to be more than bright enough for any daytime viewing in my room although I understand that is not enough for some people or preferable.
Anyway, just my two cents coming from someone who actually had both sets in his living room.