hmmm i dont know.
i played for the first time in a tournament yesterday and i didnt notice if it was stronger depending on where you hit with it. but i can tell you his f smash was one of his best killing moves.
i killed marth with it on the animal crossing stage. we were fighting on the very right side, and he died out of the left side.
as far as the tip being stronger i dont think it will mtter that much. for at least what ive seen right now brawl will be a game that involvesmore walking up to your opponent with tilting and perfect spacing. kind of like a hugs style of play from melee. except every character does it. unless their jumps are broken.