I've discovered something interesting, frustrating and disturbing.
The original versions of SoMI were made in a 640x400 resolution. Not 640x480.
What this means is that the "Aspect Ratio Correction" option in ScummVM, when checked, stretches the image to fit a 480 pixel high resolution, but that also means that the images ingame are 20% taller than originally designed. I have confirmed this by also running EGA SoMI in DOSBox without specifying any resolution settings.

ScummVM: SoMI EGA without ratio correction ------ ScummVM: SoMI EGA with ratio correction
It also means that SoMI:SE's Classic Mode
also stretches the original image to fit the screen. It just goes about it a bit differently than ScummVM does (similar to how it affects images differently in Photoshop when you resize using a different resample method.)

ScummVM: SoMI VGA without ratio correction ------- SoMI:SE Classic Mode
It
also means... *sigh*... that I'm going to have to redo my sprite icons on here.
Indicentally, the VGA sprite icon I made came from SE classic mode.