I drank with him then had a nice, friendly, fight to the death. The fight was a lot easier than the one in Act 1. My rationale was that I spent the entirety of the game trying to find him. So I was not going to let him go.
In my 2nd playthrough I will most likely not kill Letho or the Dragon. I'll be interested to see if it actually has any impact in The Witcher 3
I fought and killed him, was always going to do so. I spent the whole game searching for him, wanting revenge for him killing the king and wanting to clear my name so I wasn't going to have a drink with him and let him walk away. He needed taking down a peg or two ;) The fight was really wasy aswell, run around that square, dodging and blocking then hitting him a few times, easy!
Let him go. I wasn't out to avenge the king(s) killed, besides I kinda let Henselt die earlier... And he pretty much cleared my name and shifted the blame of off me by implicating the mages. --- http://i33.tinypic.com/14xfabl.jpg Memento vivere, memento mori
I let him live. If it's one thing I learned from Mass Effect 3, it is that you will miss out on a lot if you choose to let people die. Let them live and you'll meet up in the next game. Let them die, and they will never be spoken of again, and no one will bother mentioning the choice you did.
If he ends up saving Triss, then I let him walk away out of gratitude. But if I end up going after Triss, then I kill Letho because I promised Roche that I would.
In both cases, we share the bottle of vodka before anything happens. Because, ignoring the final outcome of the day, we were both friends once. --- "At times we must purge things from this world because they should not exist. Even if it means losing someone that you love" ~ Deadly Premonition
Two playthroughs down, one killed him the other spared him. What's great about Letho is that he is a very grey character. He does some good and also some bad. --- https://www.playfire.com/bestgame/JWYRXZ