Dism++ or Dism is a housekeeping utility for Win 10 to clean older files and Trim W10 Size after every update. After removing everything W10 is just faster and less bloated.
Is it any better than simply using Ccleaner updated with the lastest winapp2.ini file? That's what I use (plus a registry cleaner) and my system runs great. I don't care what anybody says, Windows is notorious at leaving behind garbage and tons of useless registry keys. This is why I believe cleaning is an absolute necesity.
I never upgrade W10, just Clean install everything. I did upgrade only once to get W10 using W7/8.1 license.
You're going to have to make the jump to W10 sooner or later, and especially if you have a relatively new system. I don't procrastinate - I went with 10 and ironed out most of the annoyances.