A4, they problem that you had with the gearing is something that I won't have to worry about. My mount lets me use a 9T pinion with a 44T spur. If I go with the 1512 1.5y, I'm thinking along the lines of 12-14/46 gearing. If I go with the 3D, I'm thinking 14-16/46 for the gearing. I really like the 1700kv motor. It does all that I want. If the 1512 3d will perform the same as the Feigao 9XL, but run lots cooler, I'll be a happy camper. The 9XL already has the potential for more torque than I can use. If the 1515 puts out more torque, I don't need it.