Apples to oranges. SS brake lines and larger brakes both reduce fade, but that's where the similarities end. Larger brakes will give you more friction surface, better heat dissipation (SS lines don't dissipate heat, they just don't expand when hot), less likelihood of warping rotors and better all around performance. All SS lines do is stay semi-rigid when hot. The amount of heat it takes to make a noticeable difference in a rubber brake line is beyond what most of us will encounter in our 4runners except maybe towing a boat down a long mountain pass.
I upgraded to SS lines in my old race car, and you really didn't start to feel the difference until a couple hot laps in (that is a LOT of heat!)