My thinking is this:
- Cables rarely break.
- When cables do break they show signs beforehand in the form of fraying. Check for it especially in the first inches of cable at the shifters and brake levers. If you see any fraying at all, replace the cables before the trip.
- You can limp along with any of the four cables broken.
- On the other hand if it makes you worry less, take them. At least they don't weigh much.