@Stuffdone
I tested it a while ago. Although I don't remember the details but, yes, it is useless.
You can reduce the the polygons of a character but you CAN'T save anything of what you just did....!!! I have searched the forum at DAZ and got it confirmed that the reduction is just temporarily and impossible to save in any way. The reason is very technical and I don't remember the details (the result is somehow not compatible with .DUF).
I believe Decimator would only work if a script kicked in whenever you open a scene or merging a subset - that contains a previously decimated character - the script would have to repeat exactly what you did in a previous session. That's my understanding...
If anyone has been able to save the result PLEASE tell what you did! I really would have an enormous use of being able to create a library of small poly characters to be used in the background!