For 70" class 3D planes, no use for 8" of pitch here. At 900' asl, I run a Zoar 20x6 for increased vertical power, shorter take off runs, less tendency to build speed on down lines, and will slow to a walking speed on final approach very quickly. Increased (max) diameter means more air blowing over my control surfaces at low air speeds for increased control. Still plenty fast enough.

Point being, experimenting with different size props with YOUR priorities in mind, can often pay off handsomely. -Al