It is VERY noticeable in FCoB. The thing is that it seems SE balances Physical attacks around healers, so an unavoidable mechanic needs to be at least survivable by mages who have the least Physical defense. However, the team balances Magic attacks around other DPS's, so they only need be survivable by MNK/NIN/BRD, leaving DRG in the cold.

It's got to the point where we have to take extra precautions to let our DRG live. We crafted him some i90 VIT-melded accesories (Comlpetly uneeded by the other DPS classes, and further impairs his DPS), we have the BLM use Apocatastasis on him for any big hit, and he is perma-stoneskin'd for T10 in case he gets Prey (Since Adlo alone won't save him). We don't take this precautions with anyone else, unless they are weakened.

To me, it makes no sense that a class with positionals, closest to the danger and wearing a heavier suit of armor than everyone else takes more damage. Specially considering DRG shared a lot of TANK items at lower levels. If anything, their magic def should at least equal MNK/NIN/BRD.