Now as far as the published noise levels, I have never measured them with any type of measuring device, but I can say for fact that my Honda 2000 is alot quiter than my Onan 4000. Only time I use the Onan any more is when I need the A/C on or need more than one large appliance operating at one time.
I have a friend that has the Honda EU3000 and he says he is very happy with it! When he turned it on, you could barely hear it. He was telling me that he can run his A/C and it runs fine, but if wants to use the microwave, he does have to shut A/C unit off. If you haven't priced them yet, get ready! My friend got his on E-Bay and paid $1600. That has probably been the best price so far that I have seen. If anybody out there knows of better pricing, please let me know. That's why I haven't gotten one yet!
We recently sold our Honda EX5500 and upgraded to the Honda Eu6500ie for our embroidery business. We set up at dog shows and the judges are very particular about noise and possible distractions. We have never been told our Hondas were too loud and usually people commented on how quiet they are. My Honda 6500 is quieter than my Onan 5500 that is in my motorhome. I have seen people using the Yamaha 3500 and that is very quiet also.