Luckly I've delt with someone like you before who questioned Durans P4P status. (Not that theres anything wrong with questioning)
But people don't look at the big picture...
A boxers greatness is not measured by 1 or 2 or 3 things. It's a mixture of a handful of things. Durans great because he fought through adversity because he beat all time greats. Because he fought the best of his era, the next era and the next era. Because when he has listed as the underdog he came out on top, because when they said he was done he won. Because his skills were amazing because he could adapt to any style in the ring.
Here's a post that should put things into light a bit more for you as far as Durans career.
http://www.saddoboxing.com/boxingfor...tml#post436770