How is ilvl an issue while leveling?

[miraidensetsu]

For healer and dps ilvl 270 is pretty fine for every leveling dungeon. But for tank you notice mobs start hit pretty hard in last dungeons.

Not quite. For healers, it is harder to keep it up with the heals if the equips is aug-shire and the dungeon is 67+. Specially when your tank is also equiped with full aug-shire. It is possible, but they both will suffer more.