I have a 5500 in my Cyclone and it's pretty quiet. Just a bit of a background rumble that is not the least bit difficult to tune out. I will tell you this, if you have a bedroom A/C unit you won't hear the gen-set at all.
Dont regret buying one bit. I'm not big in the boondocking scene but do generally do one long weekend of it per season and the genny is a godsend. Keeps the wife cool and happy, which keeps me cool and happy. It runs 24/7 for the weekend and it's sound foot-print is practically non-existent after only a handful of steps from the camper.
It's WAY quieter than the harbor freight specials a lot of folks show up with. Those friggin things sound like a can full of gravel in a paint shaker. :)
It's also come in handy on more than one occasion when the campgrounds we were at lost power for one reason or the other. Other people were scratching their heads and wondering what to do, and all we had to do was hit the start button. Problem solved, cold beverages all around. :)