Color-coded according to speed in editor
A feature that had been good when you are editing speed limits would be to go into a "Edit mode for the speed limit" just as the house number.
That all roads would be color-coded according to speed. and roads with no speed would be gray, so you can easily see which roads have the limitation and which have not.
Another thing that would be great is that you can put limits whereever on the road and not just at a crossing. Again, just as the house number.