It is a Sporting powder & I will caution using it in the same measurements of what you would normally use. Most shooters reduce the load by 20% when shooting it as it is a hot powder & builds pressure quicker than most powders. Aprox 80 grains of Swiss is equiv. to aprox. 100 grains of Goex, etc.
Yes, it is Consideralby cleaner burning than Goex, Scheutzen & Elephant.
Accuracy wise I find it as accurate as anything I have shot & in the small bores it is Extremely accurate. IMHO, where people error with it & other powders is they think it will shoot their old load as well or whatever. Just like any powder, ball, patch, lube, you change, when ya change one of them you generally start over & find the new load for that particular combo & especially when ya change powders.
And in a small bore, 3F Swiss is the cats meow... It is awesome, potent, accurate, clean burning, etc..... And a pound of it in a .36 or .40 cal lasts a Long time at 25-30 grains a shot...
As for shooting it in flintlocks, that is almost all I shoot & it works wonderfully in all of them.