Dunno, for some reason I am able to repartition, resize and manage my disks with the new Disk Utikity just fine. There were certainly some shortcomings with the 10.11 version (window couldn't be resized etc), but weren't they fixed in sierra? What is it that you are still unable to do?
Reminder: You are in the El Capitan subform.
Many people are not planning to update for quite sometime. Some many never move to Sierra.