I've found through personal observation "quiet" generators are truly only quiet when idling in eco mode. This is also when they produce the least power.
According to my unscientific ears, Honda and Yamaha are both pretty loud at full throttle (max output). Really, that's the only way I run my twin Yamaha 2000's; wide open - I don't use the eco mode unless it's just idling for exercise (boiling water on a timer) or running in my truck bed while I drive.
Other campers I have witnessed feel the need to run their (they've all been Honda actually) all day long, idling away in eco mode, trickle charging their batteries. To each their own I guess. I lug around 800 AH of battery so I can run silent for a few days, and then do a full throttle recharge for a few hours.
If it's into the upper 80s and I need a break from the heat, I fire the twins, up full throttle and crank on the AC. I try to put the twins somewhere their noise will be least directed at others, and as far from my coach as 50ft of cord will allow.