I thought it was just sage being undertuned, but levelling Reaper now and seeing all 4 Healers struggle and lose tanks Tanks on trash clued me in that it wasn't the job, it was the stat squish nuking healing numbers across the board.
For reference, I lost 2 tanks to trash in the entire 70 to 90 experience as Sage. So it's not that the job is undertuned, it's that we lost the broken healing power we had in the past where a single oGCD could ping a tank for 70% of their HP.