I wonder how many DA 50´s are out there 6000, 7000.... More. I don´t think you can sell that amount of engines with a missmatched carb....
I was thinking I had this same problem with my DA 50 (not able to go rich in the high end) but it turned out that was more a tuning problem than anything else. The carb supplied with the engine supplies enough fuel at high throttle settings and the transition is very good.. at least in my case.
It is also true that while the carb supplies enough fuel you cannot get this engine overly rich like you can do with other engines and I wonder if there is a reason for DA to keep it that way. It is extremely unlikely that they would not be aware of a problem like this after selling so many engines and considering that fixing this condition is very easy. If there was a problem they would have fixed it by now.
Andres