brushless 1/5 4wd conversion about to begin! couple questions.

[Overdriven]

It's says "NiCd only" because they don't want you to use alkalines, but they haven't kept up with the rimes to include NiMh and lipo etc.

Personally I'd run a 1/4 scale servo. The two you linked still have alot of torque and either should be plenty. Also I don't care how big the gears are, there's no way they can be as big as a 1/4 scales, it's physically impossible. And what about the gears in the JR is big, the teeth, dia, width? Usually what happens in standard servos is the gears get wider to increase the contact area of the gears making them stronger. Even though the standard has more torque than the 1/4 scale, the 1/4 has stronger gears so it can stand up to the shock loads that get past the servo saver.