I think the moisture problems whith American Pioneer are no worse than pyrodex or 777. I pulled out a canister of AP from my fathers basement which was more than a year old and only a couple clumps had formed, exactly the same with the 777 he had. So far I am convinced that AP is in all forms a better powder than Pyrodex or 777...

1) much cleaner (no debate)
2) cheaper than 777 (no debate)
3) same ballistically from what I can tell
4) moisture problems if they even exist are overrated

negatives.
1) not too available
2) lack of advertising!