i have the champion 3500/4000.. as well as 2 honda 2000is as well as 2 champion 2000o stackables
they all sound abou the the same with the AC running and a load on... to my ears the Champion stackables are quieter than the others in eco mode with the AC off
so in my opinion, if you are running your genset for AC it doesnt matter sound wise which of the 3 you use
so, the champion stackables are quiter in eco mode
the hondas to my ears are a tad louder but since i have extended run tanks for em, will probably go in the camper because i dont have to refill
the 3500/4000 served me well and is not nearly as loud as some want you to believe...when compared to other gensets under load
as far as champion Customer service, i bought the stackables used off the internet... for some reason they wouldnt parallel... Champion sent me new control modules for free once i shipped em the old ones.. they were falling over themselves trying to make things right in support of their product.. i told em up front how i got the units so Champion customer service gets a 5 star rating from me
jusr rambling
edit: like it matters, just picked up a used motorhome w/onboard 7.5 onan diesel gennie ;)