Dunus are a strange beast, I'll try and address the question to the best of my ability given that I've only started my "honeymoon" phase with them.
I'm coming from the Miles Davis Trumpets camp which I've grown to love: quite detailed iems with a nice smooth signature. The short answer to the mids is that it varies upon the recording (if not the eartips!).
Contrast between the Trumpets and the Dunu works for specific genres: I felt overwhelmed with the details when listening to say, the Charles Mingus Big Band on the Dn2k, whereas I prefer if not miss the laid back smooth details from the Trumpets.
I seem to enjoy hearing some death metal recordings with the super detailed Dunus! AsBloodRunsBlack or some Dir en Grey sound fantastic with all the cacophony happening around my head!
So far, as one respected head fi'er put it: it's a very silky sounding signature, this seems to hold from my impression. I definitely admire the restraint especially when I'm such a jazz fan. The detailed presentation/layout of the Miles Smiles album is a treat with the Dunu!