We have a Northstar TS 1000 with the tanked toilet system and a couple of boats with porta pottis. I have assumed that a cassette toilet was superior since it didn't require a dump station to empty and was easier to access the tank than a traditional porta potti. However. . . We did an exchange in Australia and the camping trailer had a cassette. It emitted a lot of odor. Near as I can tell, it was a result of the seal on the tank valve not being tight. It almost seemed as if the final seal was caused by a spring which held the valve up against the top of the cassette tank. Perhaps this is necessary because the connection between the valve and the lever inside the camper to open the valve is not of one piece and cannot tolerate a tight fitting spade on the tank. Our porta potti valves are one piece and very tight, as is the valve in the tanked toilet. Both will easily hold water but the cassette valve leaked the water in the toilet bowl into the cassette tank. Although the camper we used was a few years old, it seems the problem must have existed from new since the original owner had actually fitted a fan to the cassette tank compartment door to suck the odors out. The current owner had recently fitted a new gasket on the cassette to resolve the problem. It didn't work. The camper had a fairly tight fitting door on the bathroom so the odor tended to stay within the bathroom, but in a pop up camper with a relatively open plan, I would think the odor would be intolerable. Have other people with cassette toilets had this problem or do you think it is an issue confined to the one cassette system we have happened to encounter. As it stands, my current opinion is that I would not choose a cassette system for this reason.