Got a whole line of the collet styles in a nice wooden block on the loading bench. Cpl things;
Like so many Lee products,their QC is very "range'y". Some of the collet crimpers come rough as a cob,others come much nicer/smoother. It's fixable. There is some crossover on cartridges but means you need to record die height and/or have bushing or spacer made..... I've gotten to just get the right one and record height,which is in effect,set it N forget it.
One aspect is,they give you some latitude or options vs a typical,"never crimp bottle neck's". Which,is a pretty well tested procedure..... until it's not. I'd say easily 1/3rd and possibly a touch more,of my bottlenecks get collet treated. It depends on how easy the trip is,up through the magazine and bolt throw,and feed ramp,and bullet design,and.... well,you get the idea. It is also useful as a very fine tune,after you've set the bullet depth and powder charge weight..... you play with the crimp.