Hi Kirk, at least on the 4.6.2 beta 1, when I have sharpen previews turned on, it sharpens the displayed photo even if zoomed to 100% view.
In my humble opinion, sharpening of previews should be automatically turned off when one views the photo at 100%, when one wants to see the pure pixels of the photo. After all, sharpening the previews should be IMHO only done for less than 100% zoom (ie smaller) view, because the resizing process for displaying does loose some sharpness. Maybe it was intended that way, maybe not, but I do think the current behaviour is wrong
Thanks, Frantisek