I,m not entirely convinced that a fifth blade will do anything. You make one change and you have to follow up on the other components.
A fifth blade will most certanly increase drag in the rotorsystem. You then have to boost the engines in order to have the same performance, strenghten the gearbox and transmission. I have no doubt that it can be done, but are they willing to accept the weight penalties?
As someone mentioned earlier, I hope they find the aircraft best suited for the mission.
Rotordude