How does it perform in autorotation? The 500 series is sporty in autorotation, as I understand it and perhaps the 600N is even more so.
It is flying with the optimum blade for the 500, namely the 530F blade but maybe it needs an even longer blade. That might have required a blade of a different chord and an increase in main rotor shaft height to ensure clearance over the tailboom. The even longer blade envisioned for the 520L/530K proposal proved not to have the desired performance. The 530F blade is the optimum for the 500 series but maybe not for the larger 600N airframe.
500 Fan.