I fly MD series planes for SAS.I also flew DC-9's,FK-28's,767's earlier.
I find the MD-80 and -90 very nice planes to fly in all regimes.It is a bit slower than many other jetliners,we use M0.76 as normal cruise,M0.78 for high-speed cruise,however,this reduces flight-time on a normal sector like CPH-OSL by some 2-3 minutes only.
The aft-mounted engines give a very pleasant noise-level on the flightdeck,we don't wear headsets at any time as the ceiling-mounted loudspeakers are sufficient.
The planes have a tendency to become slightly nose-heavy with a full load,in fact trim changes are more pronounced on an A/C with aft-mounted engines.
The yaw damper functions very nicely indeed.It has a much more rapid response than most other jetliners,in particular Boeing jets.This means that the turbulence ride in an MD-80/90 is far superior to the 737 which wallows "all over the place",especially the 736.The DC-9,MD-80 and -90 continues to point the nose in the direction of flight with a slight rocking motion from side to side occasionally.
Seats are standard IPECO seats and are quite comfortable provided old worn-down cushions are replaced when needed.The seats can travel back far enought so as to allow a standard mealtray to be placed in your lap,something that was not possible in the other planes I've flown for SAS,not even the 767!
Instrumentation shows it's age,though,the EFIS screens being rather small,with the NAV Display being partially obscured by the control column.
I,ve ridden on the flightdecks of 737's an A321's on jumpseats,and in my view,the A321 can match or surpass the MD-80/90 flightdeck on most accounts except noise levels.The only advantage the 73NG has on the MD series flightdeck are the large screens for attitude,nav and systems display.Everything else is regarded as substandard compared to the MD.In fact,many SAS pilots who have been transferred from the MD to the 73NG regard the 73NG flightdeck as an "ergonomic slum"!
"Luck and superstition wins all the time"!