Basically, BH 209 is a smokeless powder detuned to BP specs. You measure it the same as BP in volume. You use the same solvents to clean it as your CF guns. I've gone as much as 60 shots with easy loading, and no change in accuracy. It doesn't go bad over time, and absorbs almost no moisture. If any at all. It's expensive, but worth it.
However, it has a higher ignition temperature. This causes some problems with some breech plugs. Some can be corrected with a drill. Some can't. Others give 100% ignition from the factory.