I thought about the gear reduction route for my brushless. Here are my experiences: The lower priced reduction units are offset, so they don't fit (had some, tried them, they don't fit). Got a pricey inline unit, the only one I could find, and the output shaft was 1/4 inch. Broke even selling it on eebay, figured I could just get another brushless at a lower kv cheaper than a reduction unit anyway, so I did and I am happy.

Fact is, brushless motors are cheap enough now that it is faster and easier just to buy a new motor with the specs you want than to dig around for a power robbing gear unit. I paid more for the inline gear reduction unit than I did for the new motor.