We have currently been using a Scoop Free litter box for our two year old Persian, and it's been working out great for the most part. I like that the litter is crystals and not dusty, plus it's a pretty color and doesn't look awful in the living room. However, it lasts for 3-4 weeks which is great, but the poop receptacle starts to STINK. I looked in there after three weeks and the poop was moldy and the smell almost knocked me out. Every time it scoops the new poop into the receptacle it lifts up the lid causing the smell to come out, and you can't really manually scoop it out. Plus the cartridges are expensive. I've heard the littermaid puts the poop into bags that you can throw out as often as you want, but the motor dies pretty quickly. Does anyone use either of these or have used both?