That's certainly true, Asper, but still the question was: IGG or Engine component?
Emptying IGG and curses to end the game doesn't seem like a strategy, which can be played as an engine. Yet, I'm not sure, whether this plays more like a slog or more like a rush.
If the Engine is strong enough to defend against this kind of play in the long run, then one should probably not help the opponent play his slog/rush. If the enginge can't defend against that slog/rush, then you'd rather do it yourself than spam your engine with IGGs.
That's just, what I suppose.
Anyways, whenever you do not go for an engine, IGG seems like a nice card (as long as there are curses to deal).