> the maximum deviation between G1 and G3 is only 0.1mm. You need to exaggerate the effect much more to show the difference.

Even if the difference is small, it can be very visible because of how light is scattered on the surface. This causes visible transitions when the splines intersect the sides. Depending on what you do, it might or might not matter, but there is a visible difference.

I cannot test, but I would think that it would also be felt with the fingers. Of course, it matters only if the surface is smooth enough in the first place.