I never had any luck with any size Generac. Cummins and Kohler are they way to go for me. Caterpillar for larger sets.
The air cooled ones suck.
The generator maintenance company (their primary business is cell towers) in my area is pretty happy with mine. But as I said, it uses a common Chrysler V6 engine running at 1800 RPM’s and is water cooled. That makes a lot of the common Generac oddball engine problems go away...
As far as noise, it sounds like a typical car when running.