I've got a pretty good (artist's) eye, and I can tell you straight up that your 16:9 one is stretched. Compare the two Ulysses, or the angles in the center reticle, or your orb radar, or Command's head, or anything else on the HUD that's shown.
It's incredibly minor, but it's there.
Also, when you resized them, you should have noticed that the HUD elements didn't overlap. (If they did, it means while resizing, you also changed the aspect ratio of one of your two comparison images, which, obviously, would mean that the HUD elements would definitely overlap.)
In other news, the 1440x810 calculator is done, and I'd like people to do some testing with it. Unfortunately, I am illiterate in coding, so it doesn't spit out a ready-to-use tbl. You'll need to find a template earlier in this thread and copy in the values the calculator gives you, making sure to set $base to the same resolution you entered into the calc. The only thing you need to do in the calculator is to enter your desired HUD overlay render resolution. I made it in Excel 2007, btw, so if you can't open that, I guess you're out of luck

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