All stock electronics are garbage, even the brushless ones. Call my cynical but I'm convinced they design the stock electronics to run close to the edge so it not only cuts down on their cost but also forces people to buy after market parts. Not just stock electronics but a lot of the stock parts...
Its a cheap upgrade so Id say, just try it. Make sure you use an IR temp gun to monitor temps on teh motor and ESC. My gut tells me you're going to overheat the electronics running taller than stock gearing but since you plan on going with the taller gearing in a brushless system eventually then...