There are a few classes that suffer from the ilvl sync, largely because of loss of skill/spellspeed melds which can be an issue for classes like Black Mage or Dark Knight. Off the top of my head, I wanna say Monk is the only crit reliant class left, but they also can suffer from lack of crit melds.

But aside from those, I don't think that there's really any issue with the low ilvl sync. it's deliberately designed not to be outgeared, and even the above classes can still function without their melds, even if less optimally.