In Avowed's "Fires in the Mine" side quest, the decision to stop or support Darle significantly impacts rewards. While both choices offer XP, stopping Darle provides superior overall gains.

Supporting Darle: Yields 1026 XP but forfeits any monetary reward and further strains relations between Aedyrans and Thirdborn. Lying about your actions doesn't alter this outcome.
Stopping Darle: Provides a total of 1091 XP (212 XP for the kill + 879 XP for debriefing), exceeding the reward for supporting him. Additionally, you receive 900 coins from Seynon and Kada. Looting Darle's corpse yields a Blackwood Branch (a valuable upgrade material), Wild Mushroom Stew, and two Beetle Pies.
Therefore, from a gameplay perspective, preventing Darle's plan offers significantly better rewards: more XP, substantial coin rewards, and a useful upgrade material. While supporting Darle might align with certain narrative preferences, stopping him maximizes your in-game gains.