I have a Yamaha 3000iSE, which is very similar to Honda's 3000 watt inverter, except it can't be paralleled. Down the path is a guy powering his 15K BTU A/Cs from his Honda twin 2000 watt inverters.
When running my A/C from my 3000 watt model, and he is running his A/C from his twins, the twin Hondas are louder, but not by that much. When there isn't a large load, his twins are quieter, especially on Eco-Throttle.
I can't really give accurate measurements because of sound reflections. For example, a 2500 watt Yamaha sitting in a pickup truck will rattle around more than my 3000 watt that is on the ground.
My take: They are so close, buy the form factor that you want. The twin Hondas are easy to move around, the 3000 is nice because of remote start. If the generator is mounted to the RV, remote start makes life easy in the very cold/hot mornings.
