I bought the CatGenie through the VIC program and it's been a wonderful product with one drawback: If the pellets get low, pieces of poop break apart and go under the arm. Then they get rounded enough to pass through the arm. Of course, when all of the poo isn't taken care of the unit will bake it and make your house smell like a cow barn. The problem gets solved if I keep the pellet levels up.
A suggestion for a new arm, perhaps? Make the rake slits smaller. Big enough to let the pellets through, but small enough that if little poo balls break off, they still get caught.