(re: Interaction Magazine Archive UPDATE!)
Having checked out all three documents, I’d have to say that, IMHO, the scans of the covers are acceptable at all resolutions/quality settings. Didn’t even see a difference until I reached page 6.
For the pages that have text, to my eyes, there’s also not a great difference with each of the resolutions. The “low quality” settings make the text too blurry, though.
Bear in mind that I talk about reading off a computer screen. For hardcopy, things may well be different.
The higher the scanning resolution, the less a lower quality setting will affect perceived output quality.