Is there a reason to do non-lethal takedowns?

[Jep1st]

Mostly it's just your choise and personal preference if you think the person you're about to take down deserves to die or not.
In some quests killing someone vs. taking them out non-lethally may result in different outcomes and rewards but I can't think of a single quest in the game where non-lethal would be a hard requirement for the mission to succeed. Also in some cases you may or may not anger someone if you killed the wrong person.
There's also no achievements for going "pacifist" the entire game.

 

[Garrison72]

Nope. The fact they even offer it as an 'option' is silly.

 

[cartlidge]

the only way of doing that mission with the crooked cop with both taking care of him and not pissing regina off is with a non-lethal take down. There are times it is useful but no, it's as necessary to completing it as killing everything is, it's an alternate way of play

 

[LeKill3rFou]

Nope. The fact they even offer it as an 'option' is silly.

You mean that it would be better without "non lethal" option or if it was mandatory sometimes ?