Yesterday I picked up my Diamond DA 40 XLS from its 4th 100 hourly at Moorabbin. According to the LAME who also does Cirrus servicing as well, they each have their special quirks.
Certainly having the composite airframe means that there less risk of corrosion, and less work doing inspections in the 100 hourly as there are no inspection ports to check. BUT when there was a faulty fuel sensor, the wing had to come off to have it replaced, fortunately still under warranty! When there was an issue with one of the GPSs, the rear seats had to come out to reset one of the LRUs - line replacement units.
Having glass is great, I would not fly IFR without the glass now, your SA is amazing Some of my airline pilots at the Flying Club have been blown away with its avionics and the Garmin 1000. In fact one of my good mates traded his old C172 in for the newer Garmin 1000 C172 after flying the Diamond.
I love flying the DA 40. Last year we did a fly away with some mates from the flying club. We left in the DA 40 10 to 15 minutes after the C-172, arrived 5 to 10 minutes earlier than the C172 after a 2.5 to 3 hour flight AND BURNT less fuel!
Re maintenance issues on the Diamonds, there is an excellent website, the Diamond Aviators Network. There is lots of useful info there
DIAMOND AVIATORS NET, the forum for Aviators of Diamond Aircraft DA20, DA40 and DA42
The Australian Distributors for Diamond are currently doing a demo tour around Australia in the DA 40 and there will be a display day in Melbourne Saturday July 6th
http://www.hawkerpacific.com/events
Safe Flying
JERR