Jut make sure you get 2.0 Thielert diesels with it, i just read the december article in aviation consumer and diamond says they had 22 in flight stoppages of the 1,7 diesels !!! 22 ? Blimey!!
My club can vouch for two inflight stoppages of 1.7 Thielerts. Well, in both cases not in-flight stoppages but severe loss of power leading to forced landings. Both with good outcomes, fortunately.
Having said that, one of the inflight problems was an almost full loss of power and the incident was fairly recent. I do not know if the cause was already determined and what the cause actually was, but the issue was sufficiently complex that this aircraft (a Robin DR200-135 CDI Ecoflyer) had to spend a week or two in the field where it landed. (And for those who are not familiar with the type - the Robin has wooden spars and are normally hangared. Yes, the aircraft was thoroughly inspected before being brought back into service.)
The other incident involved a Diamond DA-40 TDI with the 1.7 engine, and was traced back to a damaged ECU Auto/B switch, leading to perpetual FADEC resets and eventually an undocumented (as in "not in the POH but in the maintenance manual") "failsafe" mode where you have 0% or 100% power, but nothing in between. As all Diamond owners will know, this ECU Auto/B switch is dangerously close to the "flightpath" of your feet when entering/exiting the aircraft. All our switches now have guards on them to prevent further similar problems.
So in at least one case, the cause was not the 1.7 engine itself but to faulty input to the FADECs. I doubt whether the 2.0 engine would have less problems with that. I mean, we all know that intelligence is normally inversely related to cubic inches, do we?
What worried me more when reading about the DA-42 is the fact that a sufficiently charged battery is absolutely essential when retracting the gear. The alternator(s) cannot, on their own, supply sufficient current for the gear motors, leading to a loss of voltage which in turn leads to all four FADECs packing in. Long thread about this about a month or two ago. If you ever need to use external power to start, read the POH!