Iron vs. Aluminum And Their Effects On Handling

[INTMD8]

As you've already touched on, engine position has to be considered when determining how much weight will have an effect.

(Is it all behind the front wheel centerline or is the weight partially leveraged over the front wheel centerline).

Of course lighter is always better and I would say the difference would be at least slightly noticeable to most, especially if you've had some time with the car with an aluminum engine to start.