JasonB,
Did you notice any improvement in accuracy after using the crimp die?
I've used the crimp die extensively. I've not noticed an increase in accuracy, but I've definitely not noticed a DECREASE in accuracy, and I like having the security of the crimp. I use them with any bullets that have cannelures.
I don't, however, crimp non-cannelured bullets like Lee suggests that you can. I just can't get over the notion of adding a groove into the bullet with my crimp.