I'd actually give Khan a better shot, then. Not saying he'd win, but he'll have his moments before Cotto catches up to him.
Khan stops him early. While Cotto has consistently fought the best in the world, he has never experienced hand speed like Amir's. Khan's foot work would have Cotto chasing shaddows all night and I suspect that Khan would look to rough him up on the inside at times too just to show him who's in charge around here. Khan has only ever been beaten by Prescott and Peterson, Cotto just isn't on that level I'm afraid.
I think Khan plants his feet and uses his thudding jab to stop Cotto coming inside. I think he pretty much dictates this fight from the outside while barely taking a shot.
I don't know how good Khan really is yet. The last fight may give a false impression, because of the Peterson drugs issue. Against Judah, Khan looked very good; Is that the real Khan and has he improved? I think the next proper fight against a non juicy fighter will show a lot. But Cotto be will the favourite, and should win I don't see Khan winning this now.