I checked out my local Best Buy and they had the 46 inch Z4100 doing its thing. It was on a separate feed than the rest of the tvs and it was playing a Blu-Ray player. I noticed the 40 inch 650 was nearby and it was playing Pirates of the Caribbean. So, I asked the sales associate if he would throw Pirates up on the 46Z. He was happy to comply. Now, something you should know, I have been trying to figure out whether I should buy the 40z or 40 inch 650. I am neither a fan of Sony or Samsung but I know they both make some of the best LCD's. So, everything I saw will be unbias observations and hopefully it will help others who are trying to decide between these two tv's.
First, the 650's colors had a lot more punch to them. The blacks were generally more black than the Z. However, this was impossible to test because Best Buy's lighting is crazy bright and it really has a way of making matte-finished LCD's look washed out. I would imagine in a dark room they would be a lot closer in black level. One thing is for sure, the Sony has very good blacks, you could tell just by observing the tv up close. It made other matte finished LCDs look gray.
Second, the 650 had a great deal of POP to the colors but, the colors felt somewhat unrealistic compared to the Sony. These are probably factory settings and so those can be adjusted. But, it would seem out of the box that the Samsung's colors were a little exaggerated. This might be untrue since I have read in a lot of places that Samsung's colors were very accurate. Maybe the Z's colors were just more washed out because of the lighting.
Third, I believe the green on the Sony was pretty mediocre. I would have to see more sources and stuff.
Fourth, I think it is safe to say that the Z does 120hz motion much better than the Samsung. This might sound crazy to some people. But, after I watched both sets for awhile it just became apparent that the 120hz on the Samsung made things look unnatural. Everyone knows that 120hz has a soap-opera effect, but on the Sony this was more subtle. Yet, not subtle in a 60hz way, more like subtle in this is being processed better and everything is operating much smoother.
Fifth, this might be irrelevant for some, but the Sony had a much nicer design overall. It's slim bezel really makes a difference on the eyes. I think the red ToC is distracting. Though the glossy and matte finishes probably wouldn't distract from my personal viewing because I mainly watch things in a controlled dark room.
Sixth, while I was waiting for the sales associate to get the remote control for the blu-ray player, i sat there and observed the black parts of the Pirates of the Caribbean intro screen. I DID NOT see any sparkles at all. I looked pretty hard. It was such an underwhelming issue when I finally looked for them. I thought I would see something. (Keep in mind they had this model set up by itself; so less interference).
I already ordered the Z, and it will be coming to my house sometime next week, so, the final test will be to unpack the Z and see if the lighting was a major problem or if it is being outperformed in the colors department. However, I am open to returning it and getting the 650. One thing that might be a deal breaker for the 650 is that you can't adjust any of the settings while in game mode and I will be doing a lot of gaming. That just seems unreasonable over the long run.