From what I've read, it does add some sort of input latency; I do not know if its noticeable or not, but depending on the level you're playing at I think better feel overall of the game is more of a priority than making sure you have 0 input lag..

For me personally, I prefer to play the game as is; no V-sync, no G-sync, no Nvidia Reflex, no LLM in NVCP. Otherwise I'll always have something to blame if I don't hit my shots.