I have two of the petkit puramax 2 for 4 cats. I am away from home for up to 4 days during the week for work at times and I never come home to messes, clogs, or errors caused by the devices, just the occasional bad shot from a cat that has been pooping over the front ledge of litterbox entrances since she was first litter trained. the only thing I don't love is that the waste bin stays in place while the bin rotates above it causing the clumps to come to a peak prematurely setting off the full box alert. a quick shake levels things out and allows the bag to be used to capacity. otherwise they have some nice settings in the app such as sloshing around the litter a little before collecting to make sure it has clumped well. they go on sale quite often from what I've seen, I believe I paid around $350 each when they were on sale.