I bought my machine with one....and I already go man I need that thing.
IMHO the rake part I have not found to be real useful...the tines are too far apart to really "rake" anything then big brush you are going to grab....kinda push it into a pile before the grab.
I have the smaller unit and I am so far real impressed with the power of the bite. I have had stuff just on the tip of the teeth and it held on and put enough force to put dents in hedge logs.
Take some pictures as you go....I really love mine.