E.,
I consider myself an expert in this dept. I have 2 adult cats (at one time had 4) & have used the automatic litterbox (littermaid) for about 10 years.
Pros & cons to these.
Pros
if you have a picky cat, the excrement is sifted out of the box.
cons
the tray that holds everything needs to be emptied daily.(don't change the container everything those things are $$$$)
You need to make sure there is not too much or not too little litter- so it get cleaned out effectively.
Periodically needs to be taken apart & cleaned. This is a PITA & takes time. You don't want to get any of the electrical components wet or it won't work.
You can use only clumping litter.
It can run on batteries but takes several D size, so needs to be plugged in all the time. With 2 cats being use to 2 litterboxes need 2 boxes.
It is somewhat bigger than average, sides are higher than average. Ramps are available. When I had my 20 yr old cat I had to change to a dog litter box so he could get in it due to his severe arthritis.
It can have electrial/mechinal problems. I have had 4-6 new units (using only 1 box at a time), but my husband is handy, so he combines pieces when need be to make 1 functioning unit.
I know it seems like a lot of cons, but if you can live with it- great.
I do recommend getting the biggest, heavy duty type.