Take off props are low pitch because they allow higher RPM and thus more HP. Cruising pitch is higher because you do not cruise at full power. Cruise is usually at higher altitudes and the adjustments are made using manifold pressure for max performance unless you have a fuel injected engine. All the above is true for full scale. I too fly at 5,000' ASL and generally use about one or two inches higher pitch for fun flying. For quicker takeoff and more power, lower pitch will do the job. If your engine will not deliver the power you want you can up engine size or go to lower pitch. I usually choose the next size up on the engine. The recommended engine size on the box for most models must be calculated for 2995 inches of mercury at
65 degrees F at sea level, (standard atmosphere). Most models flown at higher altitudes are usually underpowered when using the engines specified by the manufacturer.