Some on board generators are quieter then others. The Onan 5500 is one of the quiet ones. Friends had an Onan 4000... that wasn't one of the quieter ones, but nothing like a contractor grade generator either. The advantages of onboard are considerable; resale is usually better with one, they are with you and ready to go, you don't have to go outside to fire up your generator and finally you have a larger gas tank so you don't need to refill it. There are times when we traveled with our Raptor we ran the generator to cool things off before we arrived.