we all know Locke does, and Ben thinks Locke brought Cooper to the island, but what if it was Sawyer? what he wanted most was to find that man and have his revenge. maybe that stuff Ben says to Locke about needing to let it go to move forward, maybe it applies to Sawyer?

Definitely Sawyer needed to move forward, I mean carrying a letter around for however many years to show the guy before you kill him!! I'd say he's gotten that closure now!
As for Sawyer bringing Cooper there, I don't agree, either it was Locke or Ben. I can't take anything that Ben says at face value,so when he says that Locke brought him there I can't fully believe it, although I do think it's possible that subconsiously Locke brought him there.