Not sure why I have a different experience with it. The S last that I have feels a little tighter than my U last. My right foot is a bit wider and it's tight on the S last but fits better in the U last. This was confirmed by Rezső as well. When I get S last in different sizes, I'll ask some of my clients and maybe we can get a verdict.
The overall fit of the S sounds promising to me (lower instep) but the toe box looks too "square" from pictures. It looks wider than G&G's TG73. I was planning to pick up an S lasted shoe in the future but I might have to wait for there "other" lasts to show up and identify their fit/shape.
Interesting that there is now a Vass and Spring Line connection!