Thanks for the reply. I'm absolutely with you in terms of pixel count. It's more quality/accuracy that I'm concerned about.
Unless I've misunderstood, when you look at an image at 1:1 zoom with 100% scaling at your display's native resolution you're seeing something as close to possible to the actual image. This is why people go to 1:1 to check focus, sharpness, noise etc. When the windows scaling gets involved, then additional scaling has been applied to the image and you're no longer seeing a 'true' image. Specifically, you're likely to see a softer image. I'm very much open to proving myself wrong, so I'd quite like to try and test this out with some test charts when I get the chance!