I had a LitterMaid for two years. I loved it at first. I found that if the cat peed a lot, and the litter didn't clump hard enough in 10 minutes, you got a lot of mushy, clumpy, sandy pee stuck in between the rakes. Then, when it raked again, it piled up until it got really hard and only raked huge clumps of sand which made the machine stop and re-rake again, and again, and again. I had to constantly use a knife to scrap off the stuck clumps and then hope it didn't get stuck again in the middle of the night (which happens, and you have to turn off the machine).
My cousin bought one and returned it because the machine scooped it out of the box and onto the floor. Cleaning the machine is not easy either because the litter gets stuck into all of the crevices. I liked it at first, but after about a year, it was too much work to get it to work, so I dumped it and went back to scooping it myself.
Hope you have better luck.
P.S. If you have a big cat like me...13 lbs. it's hard for them to move around comfortably. Plus, if they kick up a lot of litter, you'll have it all over the place.