AFAIK the german planes need the addition of some sotre types ( R4M rockets, underwing pods ), and as it's been mentioned, rudder stiffness at high speeds.
Erich's video is a great watch, and it's nice to see that some of his comments have been taken into account ( you couln't hold the 190 on full power on the brakes before, the tail lifted ).
These planes are amazing fun to fly, and there constantly remains some room to improve your flying, even if you think you've mastered it.