That's the main problem with RS6 brakes, considered totally inadequate by many. The pad area of their 8-pot Brembo is much less than even the S8's 4-pot Brembo, and obviously much less than this 6-pot Movit caliper.

All of which leads to another disadvantage of less pad area ... the pads run hotter. On the RS6, it's difficult to find pads that don't fade on track. Hotter pads also means hotter pistons, more heat transferred into the brake fluid, and an increased likelyhood of brake fade from boiling brake fluid.



But back to your original question ... Without knowing any better, I'd assume that in this respect, brake pads behave like tires. The total friction of a pad (or grip from a tire) is almost but not quite proportional to piston area (or the vertical load on the tire).

The black line is grip versus vertical load available from a tire. As a result, a larger tire footprint gives more grip, even though vertical load is the same. I believe brake pads behave similarly.

2001 Audi S8
2007 Toyota FJ Cruiser