Interesting experiment I tried - when zooming a 4:3 SD image, the generated image is actually noticeably smaller horizontally and vertically when output from the 722 at 720p vs. 1080i.
This difference is not seen on HD channels, nor, for that matter, with SD content output from any of my other devices that can output SD at 720p or 1080i, but only from the 722.
As an example, when viewing AMC at full zoom, the bottom of the AMC logo completely fits on-screen and very thin pillar bars are seen on the sides when the 4:3 image is output as 720p.
But when output as 1080i, the bottom horizontal line of the AMC logo goes missing and the image fills the full 16:9 screen.
Anyone else? Artifact of the 722 or of my display?