I load it in 45-70 for my C. Sharps 1875. I use cast 480 grain pointed semi-Postell style bullets (Lee 459-500 mould) with a cardboard overpowder wad. I use either Federal 215M or standard Remington LR primers. The bullets are greased with a beeswax/coconut oil mix and a seated with a decent crimp as suggested in the factory load data. There was a good Handloader magazine article on loading BH209 in cartridges a few years ago.
I have had excellent results from the powder so far, and have used about a can-and-a-half.
It cleans up easily, though I think it may be mildly corrosive/hydroscopic in the long term. If you shoot, then wipe the bore with a couple of dry patches only, then let the gun sit for a couple of days it will develop a fur-like coating on the inside of the barrel. I've done this a couple of times, once intentionally to see if it would happen again. I have cleaned the bore out properly with normal smokeless cleaning solutions (Hoppes No.9), and oiled the bore properly and no further coating appears. If left dirty, however, I think it would gather moisture similar to black powder and cause pitting or frosting.
I think it is an excellent powder, if expensive. It just needs a bit more diligence in cleaning.