I have two huge cats and have 1 Mega Advanced Deluxe littermaid and one of the smaller models.  I am finally free of being Queen Litter Scooper.  I also save money by cleaning/washing out the dirty receptacles and then reusing them.  I dump the waste in two small garbage bags - seal them up and toss in the garbage pail - no smell. These litter "minders" are not supposed to take away the job of cleaning after your cats - you still have to monitor the waste that gets through the rake people - so you don't have to scoop every day - you can miss a day or two, but that's it -and for us who have more than one cat it really is a blessing.  I would highly recommend them.  Also, if your littermaid stops working (light on but not moving to clean up) - call them up - they can be rebooted - YES YOU HEARD ME CORRECTLY.  This happened to mine - I thought I had to toss it out.  If you call them they'll tell you where the buttons are to reboot them.