It doesn't really enhance accuracy.
It has a carbide ring and post sizes as it crimps.
It also crimps slightly differently than your normal taper crimp. It's less sensitive to case length, where most crimp dies crimp different length cases differently.
Once adjusted it sorta 'irons out' case bulges formed by incorrect die adjustment or incorrect application, etc.
All your 9x19 ammo will fit in all your 9x19 barrels, if you use the LEE factory crimp die to crimp.
It doesn't seat, a seperate die is required for seating.
Seating and crimping in different operations is also a very much approved procedure in progressive presses.
Using different dies to seat and crimp really would take care of most wrinkles, other than trying to seat oversized lead without belling enough or using the wrong seating stem.
If you are having these problems, then it will help you with that, but in and of itself, it won't increase accuracy.
I use 'em, I like 100% reliability. They also seem to be better for crimping plated bullets for some people.
Love 'em or hate 'em, most people will agree that ammo crimped in FC dies WILL function in your gun.