I just deleted all my old worlds.  Needed the gigabytes of drive space back.  It was sad, but...  life goes on.  However, there's one world I could not and did not delete...  my Ultimate world from 1.4.7 days, which is still my best world even tho I haven't played it for at least a year.  I've played a lot of modpacks since Ultimate, but that one still seems to have been the best in my opinion...  of course, there's a bias involved - Ultimate modpack was the first time I had ever played most of the common mods.  When you've played a mod in 6 or 8 different modpacks, it does unfortunately begin to get a bit routine and loses some of its charm (thru no fault of its own).  But yeah, MJ will just be a memory I guess even tho it will live on in my Ultimate world until I finally delete that one too someday.