I don't load 45 Colt. But I have a lot of experience with HS-6 in the "other" revolver cartridges (38/357, 44 Mag/Spl).
I'll tell you that it burns cool so it's rather well suited for lead. But it doesn't ignite easily, so in large cases (i.e. revolver), I do strongly recommend a magnum primer - as USSR stated.
It also performs best with heavy bullets - I think you have that covered with the 250's.
And it also performs best when you wind it up pretty stout. Now I don't know exactly what that means in 45 Colt. All I'm saying is to not judge its performance until you work up the load were it cleans up and starts giving consistent results. At which point, I think you'll be pleased. Will it outperform (more velocity than) Unique? I dunno. My gut tells me no. But I could be wrong. Since you already have the propellant, I guess you'll find out in due time.