Hallo !
The turbulator device is really interesting to say at least and I'm surprised to hear it makes a noticable difference as I thought that the airfoils we use are much less critical in boundry layer separason compared to gliders and pylon racers.If that's the case I have a suggestion for Henning.It seems like you have put the turbulator parallel to the LE of the wing ,this means that it doesnt meet with the foil at the same chord percentage from root to tip.Theoreticaly there is an optimum position ,lets say20% (that would be my wild guess as for laminar flow in our foils).If the root and tip share the same foil I would put them in the same chord percendage.If it made a noticably difference with the parallel LE setup , it would make even more with the %setup.
Worths a try for sure !

MalteS ,
rolling tendency in inverted flight suggests that the wing you see droping every time you are inverted is heavyer that the other , led weights in 5gr increments at the oposite tip fixes the problem )
You have to check for rudder position at the beggining of a vertical and side thrust at the end.If you have too much power and the plane does not slow down in vertical (nothing unusual theese days ) go with bit less throttle .
Now I have to go and make me some turbulators ! maybe from aluminum sheet...
I'll keep you posted !
Elias