I used quite a lot of SR4756 and a few others back in the 80's. But when I tried Longshot way back then, I have stuck to it for all my self defense loads. I load for numerous different 9mm's, none have ever had a problem running 100%, with SR4756 or any other powders for that matter. I'm either lucky, or I'm doing something right?
But I'm also a different breed of reloader, as I trim all my brass, I never bell the case mouths, and I don't use any crimp at all. I just chamfer the inside of the mouth evenly so bullets will seat straight, and then seat to desired oal, done. In my minds eye, I feel this method produces more consistent neck tension, it definitely produces maximum neck tension. And since you don't trim your brass, this will eliminate issues with over, or under crimped mouths. I only trim the brass the first time, after that I don't worry about it. But like many others here, you can probably skip trimming AL pistol brass, except that your taper crimp doing more than just removing the bell, or not removing enough of the bell.
GS