Do you agree with this Hot Rod magazine online article quote?

Cast iron is an easy way to make blocks with water passages that will last "long enough". It's not a wonder material, and being cast it's not even 100% dense.

Sleeves make an incredible amount of sense. Wrought materials are 100% dense, can be made of alloys which can be coated or heat treated to a wide range of properties, and will be FAR more consistent with respect to wall thicknesses and uniformity than any casting.

More power would be the result of the surface finishes and hardnesses that could not be attained in cast iron allowing for high performance ring packages and low friction coatings. There's also a reduction in the deformation seen in the walls under load, keeping more pressure in the cylinder and allowing for tunes closer to 'the edge' that wouldn't be as reliable on a less consistent platform. All those split hairs eventually add up to several hairs, and lots of races are won by a hair...

However, taking advantage of any of the benefits takes someone with a clue about manufacturing, engine design, and the effects of loading on the parts in question.