That sounds like a lot of the things that I've read about and question. I notice it recommends that you have one for every box in the house despite it learning the differences in each cat. You'd really have to, or it couldn't gather a complete picture of each cat.
Multiple cats, multiple boxes, you start losing the simplicity of the whole thing. I can't find any info for sure, but I question if it has the ability to compile all the litter boxes into one single graph for all, or does it have a different graph for each box that then requires you doing all the math each day, week, or month to get the information you really want?
Just so you k now, we don't have any "smart" devices like it requires either. I'll stick with my old flip-phone where I don't have anything going into "the cloud" for hackers to steal.