DPS display could easily be solved with a system already in game.

[Almalexia]

mnk, your dps was lowest on that last try

mnk, "yea, I was marked 4 times in a row, went almost 30 seconds without GL stacks"

"sorry, but we gotta kick you"

mnk, "..."

Which encounter?

There is only one endgame/primal encounter where being "marked" is impossible to bounce back from without Perfect Balance.