One blade more is better
Checkers, no torque to worry about.
As
Sunny mentions, thrust reduces with airspeed in accordance with the formula,
Thrust = BHP*325/Airspeed(kts)
Thinking out aloud, perhaps the increase in prop solidity with the extra blade allows the thrust to be produced at a lower blade CL and thus reduced induced drag, more of the TQ going to thrust rather than being lost to drag.
The prop manufacturer for the new PC-12 5 blader (MT) cite,
- Ground roll distance reduced by approx. 15%
- Take-off distance over 50 ft obstacle reduced by approx. 5%
- Climb performance improved
- Cruise performance improved by up to 5 kts
versus the PC-12 POH/AFM