Raiding caravans gives you low to moderate rewards but compares badly to the reliable income from doing contracts, so it probably wouldn't be a good use of time even without the cost of alienating the caravan's faction. Raiding
supply caravans can actually be sort of good, since they typically have a few noble troops with them, and you can get their gear. Still probably not worth it in general, but it's decent if you hit a Noble Crisis and you want to try prying armor off a few guards with your daggers before engaging larger noble groups.
I had a pretty cool culmination to a greenskin invasion:
I ran some standard defense, rescue, and destroy missions, and then I was told to Hunt The Warboss. I cleared a bunch of the shitty, early game greenskin dwellings I had left standing, so eventually the horde showed up to discuss their differences. It's quite possible that I could've killed them solo, but the warboss was rolling with 30 of da boyz. So I lured them toward one of the noble house's first company. Those dudes took one look at the horde, said, "
Mercs'll murk 'em," and fled, so I had to awkwardly maneuver the fleeing nobles and the pursuing orcs together. The result was a fun 34-on-30 battle royale:
Most of the enemy horde were either goblins or orc young, neither of which are likely to do much versus heavy armor. I let the nobles move first, which as usual led to them separating into two squads, one on the north, one on the south. The northern wing was mostly melee, with two zweihanders and a knight leading the footmen. It ran into the warriors and warlord. The southern wing was mostly arbalesters and billmen led by a few sergeants versus goblins, led by two shamans and an overseer. This is a pretty shitty matchup for the nobles, since the enemies are mostly-better versions of the army wings they're engaging. The boyz took out a lot of the footmen and a zweihander pretty quickly, though the remaining zweihander and knight made a good showing and stood up to them pretty well. The gobbos ate up a sergeant, shot down some billmen, and sent wolfriders against the arbalesters.
Fortunately, their center was my bros. We took out the berserkers first and easily. With the only enemies with realistic kill potential taken care of, our frontliners walked in like a slow, unbreakable wave of death. They got rooted and netted plenty of times, but they also two-shot the goblins, who couldn't really capitalize on their immobilization. By the time I snuck in a bro to engage one of the shamans, the goblin half of the horde was basically reduced to trying to hit and run. Hit-and-run doesn't work when your frontline has already crumbled; then it's just run-or-die. Meanwhile, the orcs in the north were starting to push the nobles back, so I shifted my billmen to reinforce them with multiple, simultaneous, defensive deep strikes. Five minutes later, I am cashing in a warboss's head for 10k, and I hear rumors that my mercenaries are no longer necessary.