I only ever log in to discuss Cyclops as he is still the character i enjoy reading about most in comics.
For the record, Cyclops HAS KO'd Colossus in the past. It happened in the Brood saga that Claremont did absolutely years ago. Cyke gets infected, loses the need for his visor, gets a wider angle of beam and KOs Piotr. Someone will have to tell you the issue number of UXM, as i haven't got it off the top of my head. If people really want me to research it as proof, i'll have to dig out my old UXM and quote it another day.
Also, in Asgardian Wars, Cyke outright blasts Colossus off his feet. To be fair to Colossus, he does get back up later off panel.
Also (again), in a very early issue of the All New UXM (again, Claremont's run), a fake Angel removes Cyke's visor to hit Colossus. Colossus' thought bubble states he feels the blast burning at his skin. A later issue of UXM where they are stuck in Murderworld and Colossus is brainwashed into being the "Proletarian", Cyke has his own thought bubble stating that if he increased the power of his blast, he might "cripple Piotr....or worse"....
In none of these examples stated does it say Cyke was going at full power.
I accept both Cyke and Colossus are probably more powerful and durable than they were back in the old UXM run.
All being said, my opinion is that Cyke beats Colossus. He definitely has a tactical edge, and i think he's got enough raw power in the tank to KO Pete.