I would suggest if using the collet die to also use the dead length seating die as well. It has made more of a difference in my groups than the sizing die did. Though I give a slight edge in group size to the collet die my a slight margin.
I tested seating dies using an RCBS seating die. With, and without crimp, and using the Lee dead length seating die. The seater made a 1/4 inch difference using five shot groups at 100 yards.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.