Sony's Xr 960 improve 120Hz?

I'll try to explain the best way I can so bear with me because all of this is very confusing. I've had alot of trouble with a couple TV's lately and I'm getting a new one. The first one was a 1080p 240Hz and the second one was a 4K 120Hz. Both were Sharp and both gave me problems. This new Sony is a 75" while the first 2 were 70" TV's. The new one is 1080p 120Hz and is pretty much my only option because it's in the same price range for the trade in. I noticed that the 120Hz 4K TV actually seemed to have a smoother rate than the 240Hz 1080p version. Is that because of it being 4K and/or the difference between 120 and 240Hz really no mattering much to the human eye? If so, should I be worried about this 1080p 120Hz Sony not being as smooth? Sorry, but I really need this in layman's terms if you can.

The input rates are commonly 24, 60 and 30 in USA. So the PANEL RATE is 120 or other numbers.

-> OK, since all this smoothing is done in software and hardware the effect may be better or worse depending on how good the coders and designers were. Giving the team a 240Hz panel does not give them an automatic win.

That all said and the article I noted which I hope you read I continue to turn off image smoothing since it bungles from time to time. It's not a perfect system so I prefer seeing the 60 frames as-is. What the set does with the extra frame from what I see is it duplicates it. Which works for me.

The model I'm looking to get is the Sony 75" Class 1080p LED HDTV Model: KDL75W850C. It was either that or the Vizio 70" Class 4K LED Smart Ultra HDTV Model: M70-C3.

I really don't need to have a 4K TV since I feel it's a technology that is too early for it's time since almost everything isn't even in 4K. What sold me was the 240Hz refresh rate but I'm hearing it's BS and is really 120Hz like the Sony is. My other worry, was if the 4K helped that which I have since heard that it does not. So, I guess it answers that question.

The guy at the store told me that the Sony was the better choice. Not only because of the screen size but also because it's Sony AND said that the Xr 960 processor it has makes the difference. Does that sound about right?

What matters is what you think looks better. The article did cover or broach why not keep going past 240 and more. There are also confusing at first areas well covered in too many articles.

4K is mostly all about sales. But is it 4K or UHD 4K? I bet it's only UHD. CNET has many articles about 4K but there are charts to see if average folk can see the added pixels out there. http://referencehometheater.com/2013/commentary/4k-calculator/ seems to put you at closer than 9 feet from eyeball to 70 inch screens.

As to the processor claim, I dismiss that. Why? It doesn't matter which processor is used if the coders are not very good.

The Sony 75" Class 1080p LED HDTV Model: KDL75W850C or the Vizio 70" Class 4K LED Smart Ultra HDTV Model: M70-C3? Assuming you've looked up these models. If not, then don't worry. I'm rushed for time and this is all too complex for me to learn in the next couple days for the trade in.

For reasons such as:
1. All the Vizio models our family bought a few years ago are all dead.
2. CNET's many articles about 4K. I purposely left those out since I didn't want to slam the 4K TVs too hard today.

Which Sony? http://www.avsforum.com/forum/166-lcd-flat-panel-displays/1993586-official-sony-kdl65w850c-kdl75w850c-owners-thread.html is kind enough that I wouldn't have too much trouble getting that one.

Thanks for all of your help!

You haven't even gotten into what type of source material you will be focusing on. Keep it mind that this does matter. E.g. Comcast cable box/specific channels vs Netflix stream vs <fill in the blank>.

Also keep in mind that such larger screen sizes greatly amplify noticeable imperfections in the source material/feeds, even so called HD content.

Generally I'd pick anything name brand (Sony, Samsung, LG, Panasonic) except Vizio unless my focus was on price. YMMV.

I watch typical stuff on my TV. Movies, combat sports, video games... My ONLY 2 options for the trade in are pretty much those 2 TVs. Every other place I've posted has told me that the Sony is the better buy. You think that Vizio is better in some areas? If so, let me know. I thought I was done here. lol

Viewing/doing 'typical stuff' with an HDTV can mean a great variety of very different content/sources, leading to differing results on the screen. You might want to look into this before buying anything.

If you re-read what I wrote above, it's straight forward. If you are shopping by price alone, the Vizio is ~$200 less. Although it's priced higher, the Sony would give you better post-sales support, and look a little better, spare some of the SD content that looks horrid on most (if not all) 70-75" HDTVs. YMMV.