If I had something to do with this, I do apologize. Now if taller gearing or lower gear ratio is desired for a pure rush of sexy Ferrari speed, then everything must be up to par and that includes the batteries used which should be also mentioned here. The lower one goes on the ratio, the hungrier (Not sure if this is an actual word
) your motor will get and the ESC will have to provide the juice. The main cause of failure of a ESC is going over the AMP rating of the MOSFETs. A lot of engineers I speak with tells me a MOSFET will usually handle a little over voltage better then going above the AMP rating. Now the bigger pinion will make a vehicle go faster to a point the owner of the vehicle will have to let go of the throttle sooner letting everything take a breather or it might just be that the motor is not wasting precious energy in unloaded heat. Who knows, I'm just a noob at this brushless thing.