Just going for a straight up comparison between two PoB compared to a single worg, in terms of efficiency.
Coloured lines are for "who wins".
Worg VS 2x PoB
Cost (Min->max): 252->287 vs 210->266
Hit points: 60 vs 80(40+40)
ACC, PAR, DOD: Same
DAM: 28(+6)[14(+3)x2] vs 52(+12)[13(+3)x4] (Between brackets: If they both take Accuracy)
TOU: 15 vs 12(+3 for Hard Boiled)
WIL: 13 vs 8
SKILLS:
LVL 1
FEAR: 20 vs 14x2 (Can be applied to more units)
Steadfast VS Hard boiled
LVL 2
Same for both
LVL 3
Blood lust or Hard Boiled VS Master Strike(ability) or Taunt. Advantage to PoB since it already ahs hard boiled and can get Blood Lust next level.
LVL 4
Implacable or Fierce VS Blood Lust, Fierce, Implacable. Advantage to Worg since it gets easier choices.
LVL 5
HOWL or WAR FURY VS War Fury. Advantage to Worg with Howl.
Conclusions:
2 PoB are still, in their most expensive form, cheaper than a single Worg, while providing more hitpoints, much more potential damage, and more tactical flexibility (Being two). They are however more vulnerable to fear, and have a harder time selecting some skills.
The worg has to decide at level 3 if it's going to tank more or deal more damage, not both, while the PoB can have both. However, a PoB having both Blood Lust and Hard Boiled will not be able to have Implacable or Fierce. The Worg also costs less orders than two PoB, if you're using orders on him/it.
Level 5 is a good thing for both, but the Worg can decide to either help its team or deal more damage, but that attack skill comes at a high price.
For me, having two PoB is much more interesting than a single Worg