In regards to the Lee factory Crimp Die let me say this. Before I acquired the Lee Carbide 4 die set I could NOT make my 45 ACP 230 gr. cast boolit ammo cycle in any of my 3 45 ACP pistols. This was very frustrating. I used the original Lee Loader and an RCBS 3 die set to load the rounds.
I sure it was me that was causing the problem but that's irrelevant as I still could not get he rounds to cycle consistently. I finally broke down and got the Lee 4 die carbide set with the factory crimp die and lo and behold I had functioning ammo. All I did was follow the directions and it worked perfectly even with cast boolits.
Sometimes it's just different strokes for different folks. I too know a guy that has seated and crimped at the same time and he swears by it. I just like to do whatever works. Happy loading!