The primary benefit is that the stainless lines do not expand under pressure or degrade over time like the stock rubber lines do. This translates to quicker movement of the caliper pistons and, theoretically, firmer pressure of the pads on the rotors. In other words, better stopping power.
Thanks! That's what I was kind of thinking. Figure I'm going to rebuild the calipers while I'm at it as they haven't been touched in 22 years.