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.
One difference to check out is the seating stem inside the dies. I purchased the Micro adjusting unit and pleasently found the part in side the guide bushing that pushes the bullet down was steel. The one in original seating die that came in set was plastic. Weither it was transition in production or insurance the Micro adjustment has precision to 0.001" is not known. But it made sence to not have flexible bullet seating stem. rjb