I have a ProMax dual pivot on the front of my Milwaukee. It was fairly weak feeling until I installed a set of the Koolstop Dura holders:
Mine came with the dual compound pads installed so looks similar to this:
It also came with a set of the Salmon pads, which normally would be my preference, but these dual compound ones work so well I have not been tempted to put the Salmon ones on.
These holders and pads transformed the ProMax caliper into something that stops as well as any rim brakes I have ever used. Highly recommended, although pricey.