I absolutely Love this machine. It is well made with very few parts that would malfunction or even wear out. I've had mine for over 2 years, and had to replace the brian a couple of times, but the customers service is outstanding. Now, about those granules.....
I have the Dome, the sides, and I keep a tray or rug in front - but my cats are tracking a lot of the litter out - all over my house - It gets caught in their paws. I wonder if you are considering improving the litter. It is a bit pricey, but way better than traditional.
I have a couple of suggestions - Try a round shape instead of squares with sharp corners Or maybe just a little larger litter?
Perhaps if the rake had a slicker finish ( shiny plastic), the poopies would not get stuck and smell.
All in all, Its a great invention and well worth the money for a cat household.