I've recently seen a lot of advertising for the litter kwitter. Has anyone successfully toilet trained a cat using this or a similar product?

I'd much rather flush a toilet occasionally than deal with litter, but my cats are 10 and to date I've been unsuccessful at teaching them to use a cat door to reach their box on a deck. But I do have to admit that I didn't put a lot of effort into it. (one is a bit big and tends to get stuck)

I'd be interested in hearing about your experiences.