> how does it overall feel e.g. in font quality?

> they are grainy up close

Hmm, maybe it's its "TV-ness", but the individual pixels look pretty sharp to me at a close look (no quantum dots or weird pentile arrangement, that should definitely be looked out for), but I have no other low DPI display to compare it to. My reasoning was always "it's just an LCD panel, why would it be different" and so far I feel proven right.

> I also wonder if it's good for your eyes to focus on something that's constantly far away

My appeal-to-nature-argument would be that the natural human mix would probably have been much heavier towards looking into the distance than it is now (see the massive rise of near-sightedness in cities), so it can only be better than what we're currently doing.

A year ago I was looking to get a big screen for my iMac Pro. I looked at many monitors in the 40" range, then on a whim I put my 55" LG OLED TV on my desk 30" from my face and hooked it up. Wow, it is better and easier on the eyes than any monitor I have had. I had planned to use it beside the iMac screen, but now I just mirror to the TV and have the iMac under my desk. I have used dual monitors for decades but I like one big one better.

I run it at 3840 x 2160 and use a trackball to get around. I like it a lot. LCD TV screens do not work well extremely close up but an OLED is fine even at 12" away. Text in the corner of an LCD TV is dim and poorly defined but on an OLED it is just like it would be on a 55" sheet of paper.

Of course I was concerned that the OLED screen would burn in, but it was an older TV so I took a chance.

Most days the computer and TV are on for about 12 hours. I have run them like this for 14 months now. There is no burn in at all. The overall brightness is slowly declining, but it has been doing that since I got it in 2016. (LG OLED55B6P)

It's best for your eyes to change focal distance. Staring off into infinity, staring at 75cm, and staring at 30cm are all bad for you. Find something else to look at every so often.

There are few differences between a 4K 42" screen and 4 1080P 21" screens: the smaller screens can be angled, they have bezels, and are probably more expensive in aggregate.

I use a 55" Curved Samsung 4K TV. The DPI is similar to a 24" 1080p in a 2x2 configuration. The curve provides a similar effect to turning 2 monitors toward the viewer. I don't use the height very often, as I have progressive lenses and have to really look up to see the top. But I can lean back for watching a full screen video quite comfortably. IMHO it's fantastic. For those that can still see a difference in Hi-DPI an 8K 55" would be for them. I really don't need it though and this thing costs about $600 at Wallmart.

> One thing about TV's is that they are grainy up close.

Most TV's have a "gaming" setting that doesn't try to "improve" the video feed and just passes it through.