that passive...The problem with gold-based champions... nothing's really balanced for such a champion. There's no gold-defense like armor or mr, or anything the like. And...there is a reason you can't transfer gold to characters, normally, it allows one to basically become a power house, with 2 (Ok, 1.5) champions' incomes, instead of one, including giving assist money that wasn't theirs.
As he is right now, I'd tell the carry to give me the farm for an early philostone, then I feed him my spells all game until he's decades ahead of where he should be.
I was kind of exadgerating on the whole complaints thing...but you get the point right? Onto my suggestions.
Reduce his passive steal to 1 gold stolen, or make it so he can only steal 1 attack per 10 seconds. (little less than what philo-stone would provide as income [costing 800 just to buy] ).
Can't really do anything about that gold feeding thing, however, without changing the concept, pretty much. But there might still be a problem with it.