hi ,
wow , you do take breaking seriously [sm=thumbup.gif],
anyway ,
have both version(2sound and 2 no sound), and i can say that the non smoke and sound version circuit board last ,not like the s&s version that burns easy(i burned one as soon as i went outside in the mud).

the bad side is that the gears are not well aligned and the controller is cheaper,2 speed only.
you should shim the gears with small washer,so they wont strip.

you do not need to install a fan on the non smoke and sound since the motors(black cap) are smaller and they drain much less electricity from the board.
if you have the white caped motor ,you will have to fan cool.
hope this will save you some work.

make your pins from the track rust , they wont come out anymore.
deep them in a corrosive solution 24H,then let them dry.
never had problems with my tracks and they are worn.