>>75198422I did, in my first playthrough. Didn't regret it either, the payoff for it was great. You see, the man had betrayed literally everyone -- the other criminal syndicates wanted his head because he betrayed Novigrad, as do Radovid and the Empire for fucking up royally. He had nowhere to run, nothing left to live for, and nothing but enemies left in the world.
You see him later, in the city, homeless and invalid, having been caught and tortured by the city guilds. He was blind, couldn't walk, and lived a life worse than death as kids pelted him with rocks mocking him. I think death was too kind a penalty for him.