I use set my Apple OSX display preferences to a scaled resolution of 'More Space'.
This reduces the size of text, icons, toolbars, scrollbars, etc, I'm sure a lot of us set our retina displays to 'More Space'.
With applications such as Photoshop or ACR, I can zoom into 200% which then equates to seeing an image more 1:1 (as if the display resolution was not scaled) I can then judge sharpening exactly.
Can the RRP have an option to view at 200% - mainly for those of use who use a scaled display and need the extra enlargement.
Or if a hot-key already exists to zoom into 200% please let me know.