Thanks Crow,

Mallers are an interesting blend of "prototypical" criminals and unique talents.
proto-criminals (academic background talking here): "most" criminals demonstrate a "failure" to foresee results - that's not to say they don't plan, they just don't plan iterations and potential consequences of action (hence recidivism rates) - which lends itself to your sub-points (all reasons to believe they can take on a wave of inhuman beasties, without considering the "yeah, but what about...").
Scratch and Latch presented the very clever, scheming types - and also knew very early on that smell was a factor ("...your blood will be like a beacon...")
I see the point on the distance traveled part - I chalk that up to two possibilities: 1. they really have used up all immediate resources and going the distance for AWOL members is an add-on to their scavenging for "stuff" and a new place; 2. the AWOL took off with a ton-O-stuff and that's more valuable than getting the individual members.
I think Burt's reference to the Road Warrior (...just walk away) underscores your point about having man-power: join (get jumped in) or die; then work your way up the pecking order through skill, brutality or both.
I really have to get back to work now - between the 15 min coffee break post (that lasted 25 min) and this one, I am not having a productive Friday!