A point in Snake's favor is that he's the second heaviest out of all the Brawl characters. I went to Final Destination in Training Mode and checked at what damage Fox's fully charged up-smash will KO each character. The top 5 were Dedede (71 damage), Snake (69 damage), Donkey Kong (68 damage), Bowser (66 damage), and Captain Falcon (65 damage). I can post a full list if anyone wants it. Snake also has a decent up-B recovery so I think he'll be one of the hardest characters to kill in general.