the airframes being new type of material and design are significantly less maintenance intensive than the traditional airframes. especially as they get older.
Oz3 not sure about the Diamond series of aircraft, but I've done just on 600 hours in the Cirrus and so have six 100 hrlys to look back on. Now the nice people from Cirrus tell me that their airframes are also made from that nice new modern material and are of a modern clean sheet design which if you believe what they say, ****s all over those old dinosaur Cessnas and Pipers.
However the interesting thing is, is that the hundred hourly on the Cirrus is always, without fail, twice as much as what the 210 would normally cost. In fact the last hundred hourly for the Cirrus cost nearly eight times (!!!) as much.
So yes, new materials and later design go into the airframes, but it doesn't always translate into lower costs. In fact for us, it's been the exact opposite.