Every one is entitled to their opinions; the aircraft that landed in the field is still under investigation so I can’t comment. The only engines that have been replaced are the early series 19:1 compression ratios. All the others aren’t maintained by Diamond so I can’t say.
Pitch control units fail due to gearbox metal in the oil. That’s wrong for a start, its not the CSU that fails it’s the filter getting clogged, this has now been rectified with a slightly coarser filter. The old one was way too fine.
We don’t work on the 172’s but I have heard that the earlier model 172’s take fuel from either Left or Right tanks and not both, this has been put down to supply problems not engine related.
As for the radiators I don’t know if the DA40 & DA42 Radiators are smaller than the 172 and PA28. As I said earlier since the cooling system mod and 2.7 software update we have had very little in the way of problems. DA40 and DA42 are flown in the Emirates in their mild temperatures and if the radiators are good enough for that then I suppose it's good enough for our balmy climate.
As for the quote “The reason that the rebuilt Continentals I fly don't have such warranty terms is that they don't have a gearbox or FADEC”. What’s that got to do with warranty terms? Each has its own pro’s and cons.
As for the warranty I know and did check that’s why I posted, see here
http://web.thielert.com/typo3/index.php?id=628&L=1 . All the Life Time Extension Parts are changed and sent back for examination and from that product improvements are made. This is at no cost to the customer.
Don’t confuse ECU lights with internal engine problems. Some pilots I have spoken with still don’t understand the Engine Fadec combination. Earlier software parameters were way too tight and the slightest variation brought on the ECU lights. As I said earlier since the 2.7 software these have virtually been eliminated and an option to reset this in flight has been added.