SAS
Out of say 100 randomly chosen PPL instructors, how many would you say are entirely familiar with all of the following (very old) kit:
GNS430
GNS530
KLN94B
KMD550
etc
Then you get various autopilots incl ones that can fly an ILS and their quirks, GPSS (a.k.a. roll steering), etc.
It takes only a few minutes to learn how to use the radio+VOR in a GNSx30 and how to load waypoints into it but the rest of it is pretty complex if it is to be used fully as intended - even if ignoring the fact that some of it can't be used as intended (no GPS approaches for example).
I would say 5 (5%) at the PPL level (which includes instructors that do IMCR training). This means most students will never ever meet one. I've never met one.
Now, if we assume that anyone buying a DA42 either has an IR or is going to be doing one in it (pretty pointless otherwise I reckon) then one should get more luck with IR instructors. Would you say 10% to 20%? I know of one, working at another airfield, and he is booked up solidly for months ahead.
An additional obstacle is that nearly every ME instructor will absolutely love to do differences training in a DA42 - even if he knows next to nothing about the kit in it. Unless the client is unusually shrewd, he/she won't realise it until too late.
In a nutshell, if I was selling planes like this I would run a factory course. It would do wonders for customer relationships, too.