I have been using a Champion 4000/3500 for several years. I have had ZERO problems with it. (I have never even had to change the spark plug) However, it will run either my 13,500 BTU A/C unit OR my microwave. Not both at the same time. I French press or perk my coffee.
I make sure there is stabilizer in the fuel at all times. It holds slightly over a half of a quart of oil. So I change the oil after every trip. I use Mobil 1 synthetic. (just my preference, as I buy it in bulk, and use it in my truck as well) I also clean the air filter after every trip, and check the spark plug.
As far as noise goes, I do not have anything to compare it to. With the exception of a small 750 watt Arctic Cat 2-stroke, it is the only generator I have ever owned. I typically run it for 3 or 4 hours a day, to charge the batteries. While listening to it is annoying, it is not any more annoying than listening to any other generator, and it is only for a few of hours a day. I also tend to move it as far away from my trailer as possible.
I have a hybrid toy hauler. So there is a toy deck on the front, where the generator rides. In the past, I've had a couple of sons with me, to help me pack it around. They are adults now, and typically do not travel with us anymore. It is just myself, and my wife. I can pack it around myself, but there's nothing fun or safe about it. So I just ordered a wheel kit for it.
In short, I trust the generator to run when I need it, and for the price, it was a great value.
Jeff