I can see that this can make later equipment a bit expensive. (for example I like and use the "Lighted Electric Poles +" mod. BUT that means I am adding the build time and cost of a Lamp to every pole.)

For example the Furnaces. Do you just add the addition of the earlier version? (could make long chains expensive) Or are you subtracting the material cost of the previous from the recipe? (more or less neutral build cost.)

For furnaces it looks like you are. Is this consistent for all the recipes?