I can comment on both noise and effectiveness.
I took delivery of a brand new 2015 Flying Cloud 25FB on October 2nd, 2014. We have now camped in our new Airstream for for almost 60 nights. We have found the new dusted system to be both effective at distributing heat and/or air conditioning, and being much quieter than the ceiling mount units. When I say "much quieter", this is a gross understatement.
I know of what I speak as I have a lot of experience with Airstreams and camping. I had a 2005 Safari 25FB that I bought new and spent over 1,300 nights in. I also had a 2012 Flying Cloud 23FB that I had for almost a year and spent 148 nights in.
The new ducted air is both efficient and quiet.
SuEllyn & Brian McCabe
WBCCI #3628 -- AIR #14872 -- TAC #FL-7
2015 FC 25' FB (Lucy) with HAHA
2005 Suburban 2500 Quadrasteer (Olivia) & 2011 Silverado 3500 (Fred) with Outfitter Truck Camper (Ethel)