Mutt, I only have experience with the 1.7.
Our specimen has had a lot of teething problems. Not just in the engine, but also in very minor things like the microswitches that drive the "door open" warning. I've heard similar stories from other operators, mostly here on PPRuNe, but I've also heard stories of operators who have had no significant problems whatsoever.
That is of course with the exception of the Centurion engine problems (no or very expensive spares) that hit everybody after the Thielert bankruptcy.
We only have one Diamond, which is being maintained by our own maintenance outfit (we're a large club with 13+ aircraft so we have our own personell). They obviously did not have much experience with the DA-40 but did go to the Diamond maintenance training class and have all the official tools and manuals.. After I got stuck with the "computer says no" problem at Duxford and had somebody from a nearby operator with 10 or so DA-40s flown in, that person gave me his contact details and I forwarded them to our maintenance personell. As far as I know, they've had a rather long telephone conversation between them, so that our personell now have a lot more (2nd hand) practical experience.
So if you do decide on the DA-40, make sure your maintenance guys go to the official Diamond course (don't know the details about that though) and then arrange a contact for them with somebody who maintains these on a daily basis. There is a lot of practical information to be had from them.
Oh, and there's a Diamond Owners and Operators forum on the internet as well. My club is (presumably) a member, but not me personally. So I have no idea on how good the information on there is.
Last edited by BackPacker; 31st March 2009 at 18:57.