I have posted a link to a research paper in a different comment, however it is generally accepted that 50-70 CPL (characters per line) is optimal for reading. Fast readers preferring shorter lines.
Layout wise this is why newspapers arrange their text in columns and books also generally comply with this restriction.
I agree "HN is excellent" you only need to change the "85%" on the main table to your preference, in my case "70ch" in your case to "100%".
I do wonder how much you need UW for coding, in my experience without the IDE borders and decorations usually the code will end around halfway on my screen.
When I'm using my UW daily screen I usually dock two windows side by side. and didn't find that restricting. But I am also nostalgic for the 4:3 days from time to time.
Layout wise this is why newspapers arrange their text in columns and books also generally comply with this restriction.