I have one on my 6BR seating die. They hold their setting very well. Loaded a lot of rds without any measureable change in OAL.
However, I wouldn't bother again simply because once the OAL is figured out, I don't adjust the seating stem. Might be good for playing around when load development but after OAL is established, I would be just as happy with the fixed screw top.
I like to load my bullets very close to or just on the lands. I can adjust for this without needing any fancy seating stems.
Just my thoughts...
Jerry