I have, they typically use ski/natique(sp) style boats which don't throw any more wake than other boats of similar size. It's where you are in the wake that is important, you need the propulsion from the motor so they do typically ride closer than a skiier or a wake boarder. It's nothing new and as far as I know, no one has died of carbon monoxide poisioning. As long as they are obey the no wake zones/laws I don't have any issues with them, looks like fun, they are no different than someone towing a tube or a skier.