Apart from the fixed pitch options there are a number of CS propellers with STC’s for the aircraft, at the moment I am considering a CS prop for my DR400 with a view to improving the climb and cruise performance of the aircraft, I don’t think there is much more cruise speed to be had from the airframe but I think the current speed could be obtained at lower power settings and higher altitude.
So if you have flown the DR400-180 with any of the following propellers you comments would be welcome.
Hoffmann HO-V123K/180
MTV-22B 174-12
MTV-10B 174-12.
While I’m not familiar with any one of the three props, I can share with you my experience on the factory installed Hartzell and FP Sensenich in Jodel 253 which is kind of similar to DR-400-180. To cut long story short: as an owner / pilot I would choose Sensenich any day, but I don’t need to fly from strips shorter than 500m. So it all depends on your mission profile. What flight level are you usually flying?
Those modern props might be significantly less noisy but can’t really say if you would get any significant performance improvement.
I am looking for more performance in the FL080 -100 range, as said above I don’t think I will get any more speed but am looking to do the same speed at a lower power setting as the standard prop is spinning at the MAX RPM for the engine at 75% power at FL 080.
Have a look at MTV-22 performance figures. Numbers speak for themselves.
As you say, the numbers speak for themselves, very disappointing, I can only guess the prop is optimised for towing gliders into the air very quietly forthe very noise sensitive German market.
one is free to draw his own conclusions
I would say that Délémontez did a pretty good job designing efficient aircraft equipped with cheap and mainainance free FP prop. If you would look at things from this perspective MTV’s performance figures are encouraging not disappointing 
You have a very good point , but it seems to me that the propellers avalable have one very narrow aim and that is to tow gliders very quietly and this they probably do very well by keeping the tip speed down.
Given the size of the market I doubt that that a two or three blade CS prop optimised for cruise is going be a worthwhile financal investment for MT .
The aircraft performs very well in terms of all round performance and the take off & climb are not compromised too much by fitting a cruise propellor. Most of those who fly Robin DR 400-180 probably never fly for more than two hours so the current fixed pitch prop meets their needs perfectly.I am convinced that there is more efficiently to be squeezed out of this fantastic airframe by having a CS prop but the cost is unlikely to bring enough benifit except if you have a long range mission profile.
