This would be pretty interesting for "non leveling" stuff, duties that you have to do at lv 50 or 60.

While i am torn between actually splitting the players into tiers for queues *leaning towards against it, even after having a smn on a lv 60 dungeon with all crafted 220 hq gear doing the same dps I did with smn when final coil was relevant, and that being his only lv 60 class aside others at various lower levels, and using miasma 2 from 10 meters away from the enemies*, receiving a grade would be a awesome thing, I know I would love to see if I am doing ok, especially when i am not using my main job, but, I think only 3 ranks are enough, just saying if you are doing worse, average or better for that duty. Would be interesting as well having a reward if you do a good job, something simple like, a little bit more tomestones or gil, but having no penalty for average or worse.