At lift off to a hover the X-2 is a pure coaxial rotor helicopter just like the X-59. Once the X-59 accelerated to more than 200 KIAS under power from the J-60s, the engine torque from the 2 PT6 rotor drive motors dropped to 0%. At that point the helicopter was an auto-gyro.
The question is, at 235 KIAS is any of the S-2's engine torque going to the main rotor system.
IMO the answer is; A portion of the power should be delivered mechanically to the rotors during all cruise speeds. These slow turning rotors are then partially contributing to the forward thrust and not representing such a large drag.
It is claimed that even the simple gyro-copter will benefit from some mechanically powered rotor-assist.
However, this calls for
Reverse Velocity Utilization and
Variable Speed Transmission; two features that Sikorsky appears to be unwilling or unable to provide.
Dave J.