We spend more time doing dishes, cleaning windows, vacuuming, cleaning the toilet, etc. than we do dumping the tanks. In fact, dumping the tanks is probably the easiest task we have to accomplish.
It takes 10 minutes, from pulling the hoses to storing the hoses, to dump the tanks. If they were already hooked up because we were staying awhile, it would take 5, and most of that is waiting for water to drain. And that is once every 3-5 days. How long does it take to set up and break down your contraption? How much does it weigh? How much storage space does it take up? If all of those are minimal, minimal enough to offset the cost, then it might be worth looking into. Otherwise, it is just another gimmicky 'tool' that ends up deep in the recesses of the storage bin.