I know they act as a heat sink, but does any one run some heat shrink around at least on of the battery posts?

If one of your battery wires came loose off the speed control and accidently came in contact with the other, this could be the end of a lipo for you.

I know I should learn to solder better (I'm getting there), but this could be a cheap form of insurance.

BTW, if I'm running 17.5, surely some heat shrink around one post (and only where the wire is solered on) shouldn't harm the ESC too much?