Man if you can get 7th with a deck you feel comfortable with then you might just want to stick with the cards you have and aim higher with them. Change is risky.
It depends on how long he was playing with that deck. If he was just screwing around with deck combos and then magic happened, it wouldn't be a bad idea. If this was a deck that he was using for months and slowly rising in the ranks with, then I'd keep the thing for familiarity's sake.