When we were looking a few years ago one of the trailers that we really liked had a cassette toilet in it. As I recall it was the same as sitting on any of the other toilets that we looked at that day. Same height, same seat, just a different dumping method.
Having used the truck camper late in the season and being fed by others so I didn't use the grey tank much, I often wish that I had a cassette in the camper, so I could just dump it when I got home from a weekend trip, rather than having to find a dump station.
Was at one campground once where there was a TC with a cassette toilet. He simply removed the cassette, walked over to the dump station and dumped and rinsed, and then carried the cassette back to the camper. Didn't have to break camp to dump and was good to go again!(pun intended!)
Brian