Quite confused about Robber Baron quest (hunt Wolfin down)

First of all, any actual benefit in completing the quest with diplomacy instead of fight?
Will we meet Wolfin again if we let him go? in some other quest?
If not, I’d prefer to kill him since I will loot all his soldiers and gather stuff for at least 1.5 k groschen.
And now what’s driving me MAD:
I faced wolfin and killed him and all his soldiers (quite easy indeed if you have nice gear and use potions halving damage taken and doubling damage inflicted)
Then when I was reporting it to Bernard, he said “You went to the camp all alone Hanry? Jesus!” like he’s complementing with hanry for his talent.
Sadly I died after that for a stupid horse jump just a bit high.
Then I re-played the fight but this time (and all following attempts, 5-6) Bernard changed sentence and told me “I sent you there for diplomacy, not to fight … next time don’t disobey orders”. What makes him say one sentence or the other one ?
Will it change anything if he says one or the other thing?
I think it’s due to the fact that the other times I didn’t kill all his soldiers and maybe 1 or 2 fled,… but maybe not, since I’ve counted 13 enemies in the campincluding Wolfin and (if they’re really 13) I’m sure I killed them all.