SASless - yes we then increase the collective to get more power, and on descent before landing, since we're already decreasing torque before we beep up, there is no danger of overtorquing.
For the jetranger problem - if you can beep to a higher rotor RPM (and stay within the power on limits of N2/Nr), then you will get a bit more power (power = torque time RPM). Whether you're on the good or bad side of the lift/drag vs. AOA curve is another matter. In general, if you're that tight on power, you're probably asking for trouble sooner than later.