You can see in the attached screenshot that the spacing between the "P" and "a" of "Pane" are completely different which looks really ugly. That is just one of 100% of places where this shows up in the SceneBuilder tool.

I believe that this is because we use fractional metrics to calculate the letter positions but then snap the rendered layer to pixel boundaries. The result of this is the letter spacing is randomly all over the place and looks really ugly. This needs to be fixed in both LCD and Grayscale modes.