We have the cat genie. I think it has been a year. The air freshener stuff is a cost, but so far we have barely had to put any of the liter back in it. We did have to replace some part, I say we, but my wife did it. It came with it, so I guess it is a part that wears out. I think it came with two of them. I should ask, before we need another one.
Besides that, my wife and our cats love the cat genie. It is kinda freaky, it washes and then dries (with heat) the cat litter 3 times a day.
We had the liter maids before that, even got a free one from them after ours was always acting up. The liter maid can get a little nasty and needs to be kept clean. I have a big stack of plastic waste bins left over. Our last one worked good, but like I said, would need cleaned. We like the cat genie much more than the liter maid.