Unfortunately, they don't make an automatic litter box that can meet the needs of 9 cats!
But, we did have a littermaid years ago when we only had 2 cats, and it did a good enough job. I imagine with the improvement to the blades it works even better.
I can tell you we had a terrible experience with a "flushing" litter box that connects to a water source and a drain. The mechanics worked fine, but the odor when the water would "wash" the "litter" was just unbearable. Also, it was noisy, and though the cats used it, I don't think they were crazy about it. They are super expensive, so it was sent back. That's been a few years ago and there may have been improvements, but those are the negatives I can remember.