Not always, maybe never ... 
If freewheeling props have less drag ... then a helicopter would drop slower with the rotor stopped than if it windmills? The windmill drag is a function of torque drag at the hub (cutlass bearing, stuffing box, transmission), the profile drag of the blades, and the induced drag of the blades. Profile drag goes up with the square of speed. The faster the blade moves through the water the higher the profile drag. The blade must produce lift to equal the profile drag, so the lift has to go up as the square of speed too. Induced drag goes up with lift. The faster the prop is pulled through the water the rpm goes up as does the drag. At some rpm the total of lift, profile drag, and induced drag will be higher than the simple drag of the stalled blade (fixed). Below this speed the windmilling prop will have less drag, above it it will have more drag. Replace the whirly-gigs with propellers from a wind-up model airplane. At low speed the windmilling prop will have less drag than the prop that is locked. At some higher speed the drag will be equal. Above that speed the windmilling prop will have more drag than the locked prop. "I reiterate. A free wheeling prop will ALWAYS have less drag than a fixed prop." Nope, not true. You will not be able to find any tests, backed by science that state this. You can't have a system that has three drag components that increase function of speed always have lower drag than a system that has only one drag component. In auto-gyros, the drag of a windmilling prop is used to provide the lift to fly. The area of the rotor blades is not large enough to produce the lift if they are not turning.
