After testing this proposition about which side of the film should be face-up or down numerous times, at least on my set-up, which is a very high resolution construct with some of the finest components available (https://photopxl.com/digitizing-negatives-with-a-camera-revisited/), I need to observe that there isn’t a scintilla of difference whether the media is emulsion side up or down. At 100% magnification, which one would never come close to seeing in a print, I’m getting pinpoint sharpness of the dye clouds (so-called “grain”) from either option. Here is an example of my latest retest of this proposition today:
