Is there a particular training kit that you recommend? What are they cons to this? Do they sometimes miss?
I suppose there's always a chance that they'll miss during training, but neither I nor my parents had a problem. I had a fried try training three youngish kittens, and they had a couple mishaps, but I suspect that's par for the course.
Our cat will "dig" in clean toilet water, which is a little gross. Fortunately, she won't dip her toes in soiled water. I'd much rather our cat track a little toilet water than soiled litter, as at least that has the benefit of some chlorine. We have a "no mellow" policy in our house.
A recommendation: from day 1 we've rewarded our cat with the "Greenies" dental treats. As a result, she is pretty vocal about getting our attention when the toilet needs flushing, which is about twice a day (one solid, one liquid evacuation). Another benefit that we didn't anticipate, is that the vet always remarks at how clean her teeth are. So, win-win on the Greenies.
(It is the jazz musician Mingus, and some friends are very find of this bit of trivia.)
She might like it. Although one potential issue is scaring off people by mentioning "germs". In other words putting an idea that didn't exist in many people's heads that they never thought of. Although also possible it would result in increased business as well.