Boolean add and subtract definately works as intended. If you have two or more solids in your parametric part Boolean add will make them appear as one solid inside of your construct. For instance is you have three cylinders that are the same size stacked on top of each other then without the add command you will see the defining lines between them. With the add command your objects will appear as one. A cylindar is a primative but it will work with any object that you create. Subtract works the same way but will remove the object from the display. I have included three pictures of the same object. One is normal, in one i have used the add command to add the "cylinders" together and in the third I used the add command to remove some of the middle cylinders.
I hope this helps.