I've bought Hummingbird stock gear/shaft yesterday. Hummingbird gear/shaft has pin on the bottom. Ran couple test flights with inverted J250/stock blades. It has more power and runs smoother but I need to test it with like90 blades which I've ruined last week. Right now I'm in process of installing thin heatshrink on stock blades to gain some headspeed. Will keep you posted.
Regards