I have had a number of Gas engines 3W DA BME RCS to name a few.
Other than the Carb block on the old 3W, they all are made of the same, they are as good as the person working them.
Some people a just bad with motors. I have at this time 3w -100 runs great and have DA-150 runs well and have a BME 50 run good, they from time to time need ajustment. I seen guys get mad at there motors sell them to someone else, with minor ajustments engine runs fine. Customer servive from motor to motor now there is bucket of worms.