Roger,
You wrote:
2 vs 3 blade didn't make any difference flying, but the static rpm on the ground during setup was quite different. The 2 blades have a wider more pronounced frequency through the aircraft hull where the 3 blade had a narrower frequency and felt smoother. Props I tested were 64" to 70" 2 and 3 blade.
As I understand regarding performance either one of the PROPELLERS is fine.
What is not clear to me is regarding the gear box and plane structure.
because of the vibration as you mentioned it seems that the 3 blade is better.
