Superpilot, please don't take this the wrong way. I have no hours on a DA-42 or for that matter any on a Garmin 1000.
I did my IR in a old fashioned steam driven gauge aircraft.
Now if I was to get in a Twinstar, i would bloody well know how the systems work, you are pilot in command and therefore are expected to know how every bit of kit works, otherwise you should not be there in the first place. It is easy to blame someone else, or time constraints.
Lets say you were flying the aircraft I fly, Boeing 737-800, and the Captain keels over, you have to decide what to do, if you want to go to an alternate airport how the hell do you tell the FMC???? then if you need to build some waypoints to get you there you need to be able to do it.
Being a Professional Pilot brings responsibilities, you have to know what you are doing, otherwise you do not belong in the air in the first place, end of, no room for arguments here. If you mess up in the air, you could have a mid air, with devastating results......
Complaining that you have only had 15 hours flight time is not an excuse and don't even try to talk to me about high workload....
Wait until you try to depart a noise sensitive airport, using conventional naviation, dealing with flaps and speeds and ATC for the Pilot Flying, without infringing any of the regs, its bloody hard work.
Anyway I get to do that most days, along with thousands of others, Learn from your experience and you may join us up there.
Best of luck
FC