No, it's not comparable to 227ppi on a Retina MBP, not even if it is slightly further away. Desktop monitors' ideal distance is usually arm's length, barely further away than where a laptop screen sits. This isn't enough to make a 140ppi screen appear equivalent to a "Retina" screen.
A laptop screen is usually quite a bit closer than a desktop screen because the comfort of typing on it limits how far you can push it away.
I got my measuring tape and put some numbers on this.
I sit an average distance of 75cm away from my desktop screens. The 24" screen in front of me is 52cm wide. So the horizontal viewing angle is 2 * inv_tan(52/2 / 75) = 38.2 degrees, assuming I sit positioned at the middle of it.
I sit about 45cm away from my MBA's screen, with the keyboard in a comfortable position. Maintaining the same viewing angle, the screen's visible-resolution-equivalent width would be inv_tan(x / 45) = 38.2, or 45 * tan(38.2) = 35cm. So in order to have a higher effective eye resolution than my monitor, the screen would have to have more than 52 / 35, or about 1.5, times the PPI.
Work that out with the numbers in this thread, and you get a 140ppi monitor being roughly equivalent to a 210ppi laptop screen, in terms of average view angle of a pixel on an mid-range sized display.
IMO it's not that far off the 220ppi of a 15" MBP. Definitely comparable. Especially since a 31" monitor won't be as easy to sit right in front of as a 24" - as your screen gets bigger, you end up with more head movement, and it can get tiring.
> you end up with more head movement, and it can get tiring.
They we ditch full-screen and go back to windows separating the contexts you are working with.
Most of the time, I'm with two screens side by side, 22" and laptop, separating my contexts, and keep the 22" with a text editor full-screen with a vertical split and two buffers, further minimizing head movement.
I ditched full screen a long time ago. My browser window is portrait shaped; most of my editor windows are approximately square. I don't maximize anything except movies and games. I cascade windows with the bottom left corner acting as a selection surface - cascade means these corners are never occluded. I arrange my terminals on the other screen in a grid with gaps, so I can click through to my secondary testing browser.
