Didn't read though the 15 pages so if this has already been mentioned sorry.

I would support this HOWEVER, only if you are solo in DF (no parties), AND it only showed it when you clear or leave the dungeon/trial/raid/guildhest that way you can see personally how you stacked up with completely other people, also remove the "which world they are from and use only character's initials. (to prevent any possible harassment issues)

The information that should be shown is
Job, Character's initials, average item level, damage dealt, damage taken, healing done, number of skills used, average accuracy

This way the information is on the private level (no harassment) and it can be used to help players who don't have that static "coaching" them on how to be better.