Sorry to bust the thread,but i think tommy hearns is a 10+ even at 160. His one punch kos of roldan,duran and schuler,coupled with stopping the very durable 175 andries And giving hagler the hardest single shot of his career mean more than knocking out tomato cans and not especially durable fighters. Nigel benn at 160 was also a savage puncher as evidenced by barkley being bashed in one and the de witt stoppage,both very durable guys...
Robinson was better as a one shot sort of guy than any of them, at 9, Pavlik at 8.5 Hagler at 8, and Ol' Jake was about a 5.5. LaMotta was not a puncher. If ANYBODY in the whole history of boxing was a 10, it would be Jackson, of course. Good pick there.
On second thought, the 10 for Jackson is right and the 9 for Robinson is about right, but I'm not so sure about the others I listed. I have to give it more thought.