Our coach is a 2011 and it has three 15000 BTU roof-air/heat pump units. The 42QD is still a production model and, to my knowledge, Winnie hasn't changed anything about the A/C system on the new ones. When all three AC units are set to high-cool, it sounds like a freight train is driving past us. The good news is, they cool the coach very quickly - faster than I've ever seen in any other coach. Once the coach is cool, we'll turn them to low-cool, and maybe turn a zone off, which really quiets them down.
If I had to choose between an AC system that's noisy but cools well, or one that's quieter but doesn't cool well, I'll take the noise. I guess they just haven't figured out how to make the process any quieter.
Kev