Not that I doubt your test results, but if you are just using a single pair of ears (yours), your results may be skewed because of any hearing loss you've ever experienced and because, just maybe, you are hearing what you want to hear. Have someone (without a dog in the fight) randomly listen, so that they don'y know which one is running, and see what they think. Also, since the discussion isn't based on which generator will be louder to you, but is more focussed on wheich generator might be more annoying to a potential neighboring camper, listen from 50'+ away, and see which is louder from there. It's been my experience that the Champions and other lower cost construction-site grade generators have sound that carries further distance.
2014 RAM 2500 Laramie 4x4 Quad Cab w/Cummins Turbo Diesel, 2009 Rockwood 2607, and 3 'yaks!
300W of Suntech Solar, a Rogue MPT-3024 Controller, and a Xantrex PW2000 Inverter