We did this with a design that included curves (that would look “jaggier” as raster resolution gets poorer) as well as fine detail (nearly parallel curves very close to each other).
We did not happen to include gradient fills or anything similar, such as a photograph.
Material was opaque acrylic, which doesn’t tend to have charred cloudy deposits downwind of the engrave like wood or leather does (I’m not sure of the jargon term for these deposits).
I was fully expecting that the higher bitmap resolution would make higher engrave quality (due to interpolation done by GFUI). Instead, we didn’t find any clear difference in engrave quality between the two bitmap resolutions. The makerspace director even got out a magnifying glass.
Maybe on other materials, or with gradient fills etc., the DPI = 2 x LPI guideline is more applicable.