Barbara, The front pads are generally used much more heavily than the rear shoes. We bought the CarboTech front pads from 600 and they will last a VERY long time and out-perform just about anything else.
We have a proportioning valve that takes out about 50% of our rear brake, and since they are drum brakes, they only have about 60% of the braking force of the front disk brakes by design. But the shoes I got were cheap and I don't expect them to last as long.
We have been having brake issues since we started and I just figured out the problem tonight and fixed it. We are going to be faster Saturday.