So I'm looking at buying a da42-vi right now, and I have to say, acquisition costs aside, it is a heck of an airplane. They are also fairly quick for the fuel burn (for a twin).
Comfort is improved with the reclining seat option. Overall a good plane for a western US pilot who wants to build multi retract technically advanced time, with known ice and turbos.
Edit: site won't let me attach photos yet but the image reads 143 kts indicated, 169 true, at 10,000 feet, with a 63 kt headwind for a horrible gs of 106kts. OAT was +1c.
Attached is a photo from "just" a NG version coming back from Vegas Friday (what a ride, some of the worst turb I've ever experienced, plus icing and moutains and atc holding me low oh my!).
That was at 82% power burning around 13.x GPH. Note the headwind (and thus the mechanical turbulence from hell earlier in the flight coming out of HND). Basically NA SR22 numbers but it climbs way better at altitude than a NA 550 powered plane. A dash 6 will be another 12 to 15 knots faster with even better climb and OEI performance.
The plane's dubious performance and operating expense reputation are relics of the tdi version and the -VI is just a completely different proposition in every respect.
Just a great plane as far as I'm concerned (not so much the early da42 tdi and Lycoming 360 versions though).