The 'caution' attribute definitely affects defense grouping as well. I ran the scenarios through about 10 times for each setting.
Aggression 5,
Caution 5, Tactical Skill 5

Defense concentrates to the center of the town with forward infantry screen.
Aggression 5,
Caution -5, Tactical Skill 5

Defenses more spread out. Interestingly, one of the exit flags is also defended.