Thanks for the welcome!
I don't expect I will be doing too many posts - not my scene. I was only prompted to do so by the suggestion that the blame largly lay in not adhering to a checklist.
Since I quit being an airline captain long ago I have owned a number of light aircraft - possible the 'heaviest' being a Cessna Golden Eagle and the 'lightest' a Grob 109.
By the way I flew into Schipol many times a long time ago as a very young captain for SABENA (RIP). A very hard way to build hours and earn a crust but you did get very good at doing an ILS doing eight short sectors a day.
I may stand corrected but on none of these aircraft, including 'heavy metal' airliners, did the engines stop if you had a major DC busbar failure. I do take your point that the Thielert engine is revolutionary and in fact it is what attracted me to the aircraft. I was about to buy a Piper Mirage. It has many advantages that you mention like ease of handling, and above all immunity from mishandling, so it is likely to reach it's TBO unlike a lot of conventional piston engines. However, I maintain that the engines should not stop with a major electrical problem, let alone a minor one! The way I was taught at Airline Flying School ARB lectures a very long time ago was that no major system should rely on another major system. They should be stand alone and not inter-dependant - most certainly the engines.
In fact Thielert, Diamond and EASA all agree with this in effect. The only argument seems to be who pays and whose reputation takes a knock. Theilert seem very determined it should not be them. Without knowing all the facts of the matter I would hesitate to aportion responsibility and liability. But I will say I started being sympathetic to the Diamond argument. Having learnt that the DA40 has a back up battery from this website I now lean to Thielert. If a battery backed up FADEC was available and fitted to the DA40 why did Diamond not specify it for the DA42? I expect it is very much six of one and half a dozen of the other though.
My concern is a proper fix is arrived at and the fix means the engines will not just run for one hour after a total electrical failure but for at least five hours - half the endurance of the aircraft so that when it all goes dark half way across the Bay of Bengal I can reasonably expect to reach the other side with the propellers still turning and not in glide mode!
I think the DA42 is a great aircraft with revolutionary engines and it was a 'marriage made in heaven'. I believe the owner of Diamond aircraft has said as much. It saddens me to see what seems to be rather undignified squabbiling now over who pays over such an important issue; if for no other reason than the resale value of my new toy! I can't imagine the fix will cost a mountain of money to two companies on such a roll.
I am confident there will be a fix very soon; and not just a 'read the checklist' missive from Diamond!
I have little doubt I will enjoy the new toy, particularly the running costs after a C421. It is certainly a 'drop dead gorgeous' looking piece of kit. It even has the same 'phallic nose' as the Golden Eagle, another gorgeous piece of kit. My Golden Eagle also had those wonderful tip tanks, and it made the most glorious noise - a whole lot better than a V12 Ferrari!