Kell wins. He's got too much of everything for Khan i'm afraid. Would be a good fight after Amir squeaks by Lamont, passing the torch to Kell who will go further than Amir could dream of.
I still favour Khan slightly as it happens. Not with much confidence, but still. You have to think his handspeed despite a lack of co-ordination will trouble Kell when he's pulling back and square on.