Have you tried the"Cat Genie" for multiple cats?

I don't know. Why don't you get one, try it and report back. Should be interesting. That thing will get a work out with 6 cats. I have talked to a couple of people with the genie, but none have 6 cats. I'd say with 6 cats, odds are that not all cats will use it, as some cats are afraid of it, or simply mesmerized by the cleaning action. From what the literature states, the litter material is throughly washed each time and retains no odor. Even if it does after time, you can order replacement supplies. If it works, it sure can save you a lot of time.