Stainless steel brake lines
In general, the stainless steel brake lines prevent the "ballooning" of the traditional rubber lines. New rubber lines and new stainless lines often have the same performance feelings.
I've also heard some horror stories from the stainless lines breaking, causing the brakes to fail. This is because the stainess steel doesn't flex as willingly as the rubber lines as the suspension moves. The breaks usually occur between the end-fittings and the flexible stainless line.
I would assume that if you do lots of wheeling, where your suspension moves alot, i wouldn't buy the stainless ones, and just get replacement rubber ones.
However, i do run stainless lines on the race cars, where our suspension moves only a couple inches.
Hope this helps.