100% agreed.

Previously dual monitor, 24" 1920 x 1080, portrait left, landscape right. left was usually for email and chat, right for coding and browser.

Now it's a single 40" 4k tv as my display. Using gridmove to easily partition the screen as needed. It's like have 4 1080p screens with no border. Only downside I've come across is some screensharing apps will always share the entire desktop when sharing a single app (webex is worst offender) - just the app window will be shown, but with massive greyed out background. Can be fixed by changing desktop res, just an annoyance.

Moving to a single massive screen has honestly lead to better productivity, but i possibly attribute that more to gridmove than overall screen real estate.