I filed the pitting down ever so slightly, so there are no "highs". The inner seal is what holds the pressure in, and that will only see a smooth surface. I agree , replacement is better, especially considering the price, but when a complete caliper sets me back only £44.95 none of this makes any sense really...
My philosophy is to not replace stuff just because it's old. The whole car is old. And also, I've decided to fit all the parts that came with the car before I start buying stuff. Well, that didn't last long, but I'm trying to restrain myself.