I don't use it, but I think I'd like it if I was to try it. For me the main reason I don't use it is the gun I use can't fire it. The gun I previously used could and I kept saying I was going to try it in it, but then I'd talk my self out of it. It's not so much the cost, but trying something new I think. I know I'm the opposite of most guys on here, but I really like pellets better in the field that loose powder. I like to shoot loose powder at the range though to save money. This is one of the reasons I haven't tried it, and the other one being that the Pyrodex just shoots soo well for me, I've not had a big reason to change.
I don't mind swabbing between shots, so that part doesn't bother me. The thing I think is so much better about BH209 is that it's not as corrosive so if I don't get it cleaned right away after shooting it's not a big deal.
I think once I tried BH209, I'd probably be addicted, but I've just kept talking myself out of trying it so far, and now that I'm using a gun that can't shoot it, I really have no reason to try it. If I get another muzzle loader in the future, which I'm sure I will, I may try it out.