Wisdom seems like a bad choice: consider
1. Now is actually a really bad time to bug out. Wisdom will both let you see that, and also allow you to over come your base fear and not bug out. Fine so far
2. Now is actually an idea time to bug out. Wisdom will let you see that, but will also allow you to overcome your base fear and not bug out... Hmmm...
Also the charisma of your leader should play into it, as should your intellect etc etc.
I also personally feel that wisdom is too much of a catch-all stat already. Tracking, perception, strength of will, judgement all fall there, and now so does bravery?
Finally in terms of who is likely to have it:
Clerics and druids are much more likely to be brave than fighters and barbarians. Paladins are chickens before 6th level and become indomitable at 10th.(no real reason to have high wis, poor wis saves. Get cha to wisdom saves at 6th, become immune to fear at 10).