I considered doing this with my cat, but from reading up on it, it sounds like its not less mess because cats don't understand the concept of aiming into the toilet... Maybe it depends on the size of the cat though?
I'm going to try teach my cat to fetch using clicker training. When she was a kitten, she used to fetch things I threw and then drop them at my feet.
I have strays from backyard that get to stay in when it is very nasty out. There guys are not trained but uncannily each has managed to somehow id the bathtub as the 'emergency place'.
Every cat I've ever had has been like this; if their litter box is full or for some other reason they don't want to use it, it's always the tub. I think it has something to do with the relative privacy the high bathtub walls afford them.
I'm going to try teach my cat to fetch using clicker training. When she was a kitten, she used to fetch things I threw and then drop them at my feet.