Aaron wrote
as the only person who insists on specifying snap sensitivity in document units :)
No, I too insist on it. And to make matters worse your Con is my Pro. :) You say "screen based snapping units stop the snapping from jumping across the screen at high zoom." I say "Document based snapping units allow me to enforce alignment to a grid even at high zoom." When I say enforce I mean lines fall only on the grid no matter what, and never in the no-mans-land between adjacent snapping thresholds. I still believe both camps are legitimate use cases. (And the "enforcement" camp can benefit from snapping to gridlines that have become hidden because of super low zooms too.
This is theoretical, not a use case. A use case involves you using the selector tool for moving an object on the screen, not some objects lying in the grid and mysteriously snapping to it or not.
Your argument supports my suspicion that you both are simply being facetous here.
ralf