I usually carry a multi meter to help diagnose issues. Also a slow blow fuse at the correct amperage is a good thing to have more than one with you.

For me, the extra weight of the motor and the controller is lighter than the trailer that I used to haul my daughters around.

Having to ride without power is something that I consider easier than the trailer. I have had to ride up a massive hill with a dead battery before. It is no big deal. It just takes a little bit longer.