I don't think there's any argument that a Twinstar is more technologically advanced than a Duchess or Seneca. Or that most people taking an IR aspire to flying glass cockpit jets. And I'm sure you're right, most airlines couldn't care less what aircraft you used for the IR.
I don't need convincing that my own IRT would have been easier in a DA42 than a Duchess (and not going to Cardiff would have been nice as well).
The point remains however, that if you get invited to an airline sim assessment, there's a good chance it will be a sim with clockwork dials. I still suspect that someone with a DA42 background would find the experience tougher than someone who trained in a classic type. It's horses for courses.
I was going to mention Twinstar reliability as well, then I remembered how much of the newness has worn off the Duchess fleet . . .
