Cran,
The mystery of how a Huey can be controlled even with its nominal 10,000 pounds GW is explained by the pitching moment of the airfoil it has. The trusty old NACA 0012 is kindly, and can be suspended at its quarter chord with almost no moment to feed back to the crew. All the control forces servo out are devoted to creaking the servos and mechanisms around as the pilot muscles the tip path around, little is needed by the blades.
Most modern helicopters have drooped nose assymetrical airfoils that have steady moment outputs even at low thrust, so the servos are needed just to keep the system where it needs to be. Without servos, the systems tend to go to flat pitch.
Even the servo out Huey is a handful if the rotor is taken near stall, where the pitching moment takes a turn, and the airfoil tries to go flat. The airfoil is more like a barn door when deep into stall, so the center of lift is near the mid chord point. Prior to stall, the center of lift is very near the 1/4 chord point, about where we put the feathering hinge.
I used to instruct in the H-13, which is easily flown with servos off, but gets nasty in steep turns, for the above reason.
The jack stall in the 365 family is due to the powerful blade pitching moment near stall overpowering the servos, a factor brought about because the servos were originally sized for the much lighter gross weight of the early 360/365 series, making them more marginal for the increased weight. The earlier model Cobras had jack stall for the same reason.