Personally, I've thought about the RV Airflow too, just to quiet down the A/C unit, but honestly we use the dump vents quite frequently when we arrive somewhere after travelling and the inside of the RV is smokin' hot. I love the feel of the cold air with some force, blowing directly on me to cool off after getting everything disconnected, leveled, slides out, water and sewer hooked up, etc. Once I'm cooled off sufficiently, I use a fold up trash picker-upper and reach up to close them off and let the air flow through the ceiling vents.
The thing is that with the RV Airflow system you get about a 40% increase in air flow just as soon as you would with the dump system. One of the first things my wife does on the inside is turn on the main AC unit (both if it's extremely hot) and get the RV cooling down. It's so effective that by the time I'm done outside there's a huge difference in temp inside. I can stand near the rear sofa and aim the 2 ceiling vents at me and I get more cold airflow then I ever did from the dump feature.