i'm not saying Hunt has the best chin in MMA either, but he's been tested by way more devastating strikes then Gus has.
he's eaten multiple Mirko high kicks in Mirko's prime. he's survived Jerome Le Banner's onslaughts, he's eaten JDS's overhand right and shrugged it off, he's eaten some unbelievable shots.
i'm just saying, when guys like Mark Hunt, Roy Nelson, Big Nog, and Dan Henderson are in MMA i don't know how you can claim Gus has the best chin in MMA, he's never been hit like those guys have been hit.
most of those guys chins are diminished now a days, but back when they were the same age as Gus they were eating massive shots and still moving forward.