My first experience of the 9 was a couple of years back in one of AZ's 'Super 80's' from Milan to Malta and back. Apart from the garish green seats and the oddly omitted row 13 I was incredibly impressed with the lack of noise near the front.
Having punted down to Milan on an A321 the Doug seemed almost silent up front. Got stuck down the back on the return leg though, and the narrow taper of the fuselage with the very pronounced engine noise was less fun!