I have the cut gears but I haven't run them yet. I bought them to lower the rotating mass. I do have a spare 17.5 but I have that for the B5m I pre-ordered. Speed racing products is where I bought my gears from. I've also heard of people charging a 2s battery at 3s as well. My stuff has to last so I charge at 1c and the motor is legal because I don't want to replace it.
Blake