It depends on whether or not Midnighter is too fast/skilled to keep Karnak from landing a strike on him. While I absolutely loathe to bring it up, Karnak has had trouble with both Luna and Mantis. Both with somewhat similar abilities to Midnighter, being able to predict what their opponent does. On the flipside Karnak was able to defend himself in a way that broke Luna's sword and Mantis predicted that she would eventually lose to him. I guess it can go both ways.
Seeing the future isn't the same as seeing all possibilities of a fight. There were likely ways Mantis could have won that fight. She only saw the one that would happen: her loss.
Not saying MNer wins, but it seems like calling his powers analogous to Mantis is false.