As mentioned, Perception would help against spotting bandit traps. However, it won't raise your CMAN (as opposed to SMR) defense. It would also help reduce the DS pushdown from ambushes, which was actually a factor in one of his logs:

A giantman robber leaps out of his hiding place!
A giantman robber swings a longsword at you!
AS: +406 vs DS: +246 with AvD: +17 + d100 roll: +78 = +255
... and hits for 10 points of damage!
Downward slash across your left thigh
Gouges bone!
You are stunned for 1 rounds!

However, with that endroll i'm not sure if there would be enough benefit to make a difference without additional DS from outside spells. Bandits will spawn like-level, so being able to negate their ambush DS pushdown will be quite difficult.

It's very hard to gain CMAN defense unless you're a square/semi who's willing to change your current CMAN training to the same maneuvers you're being targeted by for the defensive benefits. That more often than not will not be an option due to specific CMANs being available to only rogues/warriors.

>Given how many different areas perception touches, I've never understood why everyone isn't 1x in it

Perception.........................| 185 85

doh! one of these days.