Pascal, 75kg makes you a fly weight or jockey in this land of the great white beer belly.
I believe the main problem with the stock suspension is too much "hi-speed" compression damping.
The compression adjuster on the Sachs mainly adjusts lo-speed damping, this comes into play when cornering hard and the suspension wants to sag or collapse.
But on big bumps you get hydraulic lock as the oil can't flow fast enough so the shock cannot compress. If your roads are smooth, you won't notice the problem.
Find a 165lb GRiSO owner with a top dollar shock and take it for a ride, you will appreciate the difference.