Hallo Valier:
Another consideration about .46 or .91 fan/engines is the weight of the power plants. .91 class engines are almost twice the weight of .45 class engines. That extra weight means more structure weight and large fuel tanks, more structure weight, etc.
Remember to keep it light, and carbon fibre strands in stress areas. Use proper wood types to keep it light. When in doubt use areodynamics, not ballistics.