jgl1,
I always question that too. My R129 brakes definitely feel soft but it stops on a dime every time like Benzmac said. When I talked with the service advisor at the dealer, he commended me to have the brake worked on. But I found it astonishing that my brake can wear out that fast. Consider I do not drive the car that much -- less than 2,000 miles a year. I guess it is the design of the vehicle itself. Brakes on my W124, and W163 all act differently than one another, it seems each design has its own characteristic.

87 W124
95 R129
98 W163