I'm just using a 27" 5K iMac, BUT sometimes I change its resolution from the default, virtually 2560x1440 one to the highest DPI, which I guess is the native 51

I'm just using a 27" 5K iMac, BUT sometimes I change its resolution from the default, virtually 2560x1440 one to the highest DPI, which I guess is the native 5120x2880 and I just pull it closer and/or lean closer to it. I think for programming the 2560/1600 = 1920/1200 = 1.6 or the 3000/2000 = 1.5 ratio is a reasonable middle ground. Unfortunately it's not a common ratio among big but cheap monitors... The extra head movement required to look into the corners of a 27" or even a 25" vertical monitor definitely puts a little strain on my neck compared to a 25" horizontal one, but with frequent posture changes and breaks, while a bit tiring, I don't feel it caused any permanent damage. At least I hope it's not the reason why the middle of my upper back feels like falling apart any minute... Maybe that thai massage, when a lady was walking on my back for half an hour was a bit too much? :D