I've went from 42" 4K to 50" 4K recently and can say for a fact. 48" is too big. You really want to go 38-42" at the most. 48-50" overwhelms a desktop.

Less ppi!?!? No way.

I would say it depends on the gaming and if you are really going to be pushing 120hz if you own a 120hz monitor but are only pushing 60FPS then it's not going to really be an improvement for that. If not pushing twice the frames then I agree with Sajin that you are increasing the ppi to go for a bigger screen but on the other hand if you are getting twice the FPS then I disagree and would say that the more frames makes up for the lower ppi.

I mean, the 4K resolution is going to be WAAAY less obvious than the simple upgrade to OLED, plus the improved HDR if you are consuming such content. I mean, it is a TV really. You'll also get access to Dolby Vision content which is nice. Only real downside is burn-in (and price, I guess), which I could see happening if you are using it daily as a monitor for work or internet browsing. Just for games and movies/TV though, it's obviously going to be better.

tshalev
I mean, the 4K resolution is going to be WAAAY less obvious than the simple upgrade to OLED, plus the improved HDR if you are consuming such content. I mean, it is a TV really. You'll also get access to Dolby Vision content which is worth it. Only real downside is burn-in (and price, I guess), which I could see happening if you are using it daily as a monitor for work or internet browsing. Just for games and movies/TV though, it's obviously going to be better.

you think the OLED will be that much better than the LCD I have?  interesting.  i really need to just goto best buy or costco and take a look

tshalev
I mean, the 4K resolution is going to be WAAAY less obvious than the simple upgrade to OLED, plus the improved HDR if you are consuming such content. I mean, it is a TV really. You'll also get access to Dolby Vision content which is nice. Only real downside is burn-in (and price, I guess), which I could see happening if you are using it daily as a monitor for work or internet browsing. Just for games and movies/TV though, it's obviously going to be better.

Burn in is really something to question if it will happen if it’s constantly on and running windows since the Windows bar at the bottom is going to anyways be on screen unless you have it vanish. If you go full screen I would recommend having a random photo background and the taskbar set to vanish. As long as everything on screen goes away burn in shouldn’t happen under normal gaming unless you game for hours non stop in games without cut screens.

I agree with others, this will be way to big

I personally use a 55", mainly for medical reasons, but I also sit about 7-8 feet away from it.  I can say this much, having something this large is far easier on the eyes, and you do not strain.  But that distance, unless you are setup for it, is extremely difficult.  I have a few friends with 32" screens on their desks, and they find even those to be too large for the distance.

CraptacularOne
I would recommend you look into ultrawide monitors if you really wanna change your gaming experience. Just going to a bigger screen in the same format won't really change your gaming experience but going ultrawide will. 

This. I realize the OP is asking just about 4K screens, so my answer is a bit of a sidetrack, but if he's willing to be convinced to include other than 4K options, I think this is a pretty good discussion to have.
 
I had a 28" 4K monitor that I picked up in 2015. I loved it, but it crushed my Geforce 960's soul. I upgraded to a 1080 SC and because EVGA is awesome was able to cheaply end up with a 1080ti when those came out. Finally was getting 55-60fps, which essentially maxed out my 60hz monitor, albeit barely, and not 100% consistently. Keep in mind that a 1080ti is almost exactly the same graphics power of a current RTX 3060 but without ray tracing and DLSS. So a 3060 should be capable of around 55-60fps at 4K, at least in the games I played. Mileage will vary based on the game.
 
I eventually decided to go to a 34" ultrawide at 3440x1440p resolution at 120Hz (an Asus monitor). I did in fact notice a little loss in smoothness since the ppi figure was lower. This bothered me for a couple of days, then it just faded from my mind and I stopped noticing it. It's a very noticeable improvement from 1080p but is a bit of a step down from 4K at the same size of panel. The tradeoff was worth it to me, though, and I have no regrets.
 
The benefits of the 4K -> 3440x1440p move were severalfold. For one, this ultrawide is, well, ultra wide. I'm totally used to it now and it's my new normal, but when I first set it up it was comically wide. It's great, though, being able to have multiple documents up on my screen side by side. It's great in games having a wider field of view. In some programs like Adobe Premiere it's awesome having this extra width. I get that there are some applications where having vertical space is more important than having more horizontal space, but for everything I do the width is better. The OP will have to judge his/her own needs on this front.
 
And then there was the performance. 3440x1440p is only ~60% as many pixels per frame compared to 4k. While my 1080ti was barely hitting 60fps on my 4K monitor, it was hitting 70-120fps, depending on the games, on my 3440x1440 ultrawide. And since the 34" ultrawide has a 120hz refresh rate, this was framerate that could actually be taken advantage of. And that matters. At least in gaming, those who say that greater than 60fps or whatever is a waste are simply wrong.
 
I've got a 3080ti now, which will max out the framerate at 120++fps in almost every game I've played with it so far under almost all conditions. If I had a 4K monitor right now that could do 120 or 144hz refresh then I could presumably actually hit or approach those maximums with my current GPU/CPU combo. While that would be awesome, I would still lose the benefits of the ultrawide aspect ratio.
 
Monitor makers haven't been sitting still. You can now get 3440x1440 ultrawides in refresh rates all the way up to 180hz and even up to 240hz, with 144hz versions being shockingly cheap even compared to what I paid for my 120hz panel a couple of years ago.
 
I don't think I ever want to go back to the 16:9 aspect ratio having used 21:9 for the last couple of years. The extra width is just too nice for the kinds of uses I have for my computer.
 
Given that a 3060 can handle 3440x1440 now at playable framerates, I think 1440p vertical resolution should become the new baseline, 1080p needs to die in a fire, and enthusiasts need a new intermediate resolution. LG actually is selling a 3840x1600 monitor in the same 21:9 ultrawide aspect ratio that goes up to 160hz but will cost a fortune. For the current generation of graphics cards, though, I think 3440x1440 is a great starting point, with cards like the 3060 being good enough to drive this at playable framerates, and higher cards being able to drive it at higher refresh rates.
 
At any rate, if the OP isn't 100% wedded to the idea of 2160p vertical resolution, I think the current ultrawides would be a great alternate to consider. Unless their particular use cases absolutely require the higher PPI of a 4K screen or the taller aspect ratio of 16:9, I think the advantages of 21:9 for many uses, not just gaming, are many. The fact that all of the current-gen cards can push this resolution at playable to fantastic framerates seals the deal.

FV43U for $860+tax at amazon.  I ordered it.

It is worth it if you have freesync and or Gsync on the display. You can go Ultrawide for an improved experience but keep in mind those are more pixels to render and a small hit in performance. Also if you like older games many do not like Ultrawide displays and it's a pain to get it to work if it will work at all. It's sort of why I just stick to wide, want everything to just work new or old, 144hz at a minimum 1ms at a minimum, then freesync and or Gsync is also a must. Looking at the specs you are going to love that thing.

Well.  I have good news and bed news my friends.  The good news is that the FV43U came a day early.  The bad news is that I am completely spoiled now.
 
My initial impression is that it blows my socks off.  Its HUGE.  My desk is 60" wide I think and I have about 5-6" of total width left lol
 

 
 
 
 

Nice! I have the LG 34GP950G-B and it has been great as well. How is HDR on it?

Had the display about a week now and I put together some thoughts for those who are in the market based on a week of usage
 
* 38-42" is the ideal desktop size for me.  So far for me, ideal viewing distance on a 43" is almost exactly 36".  I started around 28-30" and I could feel the heat from the screen on my face.  Just too much.
* The difference between 144hz and 60hz is significant.
* Games are glorious.  I don't like watching movies at my desk so not sure how that is yet.
* Decreasing pixel density by going from 32" to 43" at the same 4k res has had a major positive impact on FPS online gaming performance
* HDR is a new thing to me.  HDR1000 preset is just too bright.  I use the HDR Game preset which not quite as bright
* The display generates a decent amount of heat.  I coincidentally have an external rad behind the display that helps push the heat a bit.
* The remote control is easy to use though the menus aren't super intuitive.  I still haven't figured it all out yet, just using presets
* There are no RGB/LEDs on the back like there are with the < 43" Aorus displays.  I thought mine was defective til I realized there is a smooth black area that looked like it was supposed to have RGBs but there is nothing there.
* Certain text is pretty hard to read with scaling at 100% despite 43" diag and I am 20/20ish, at least I was a year or two ago
 
Lastly
 
There are 2 dead pixels.  I've always gotten lucky and never had dead pixels before.  These are in the far upper left.. really, its not a huge deal but I am going to wait and see if it gets worse.  I have until EOM January before I am stuck with it and cannot exchange.
 
Overall
 
Highly recommended!!!

I ended up keeping it despite the dead pixels.  My only beef is that HDR dries my eyes out .  I sit just about 3' away from the screen and had to turn HDR off.. its just too much