I would like to try a set. They seem to have the advantage of a rubber o-ring that allows the die to "float" along with the advantage of being able to lock the die adjustment. Something you couldn't do with their old die rings.
I use the lee lock ring on all my dies and as stated above the o-ring allows the die to float and self center in the press. With the slop in the threads you can lock the die down off center and tilted. Any time your die is not making hard contact with the shell holder during die setup you can lock the die down off center in the threads. My old No.9 Speer reloading manual has a section on setting up your dies before the o-ring method. And the o-ring along with Redding competition shell holders will make very concentric cases. Meaning their shell holders not only control the amount of shoulder bump, but they also push upward on the die making it self center in the press threads.
In the old speer manual, you are told to place a lubed case in the shell holder and size a case with the lock ring loose and not locked down and center the die in the threads.
Then with the ram still at full extension and pushing up on the die you then tighten the dies lock ring. The problem with this method is you must use feeler gauges to adjust the amount of shoulder bump while pushing up on the die. And with the Redding competition shell holders all you do is change shell holders to adjust the amount of bump And all the Redding shell holders will push upward on the die and allow it to sellf center with the rubber o-ring.
Go with the “O” — O-Rings May Reduce Run-Out When Sizing
http://bulletin.accurateshooter.com/2020/06/go-with-the-o-o-rings-may-reduce-run-out-when-sizing/
Simple test, start your sizing die into your press and stop before the lock ring contacts the press. Now wiggle the die and watch the movement of the die and you will understand how the die can be locked down off center in the press threads. Also, note the Forster Co Ax press allows the die to float for a reason.
Adding the rubber o-ring turns your press into a Co Ax press with its floating dies, which allows them to self center when the case enters the die.
Also note that the Forster dies have a high-mounted floating expander that does not pull the case necks off center. The case neck is held and centered in the neck of the die when the expander enters the case neck. So floating dies and expanders produce very concentric cases along with Forster seating dies.