My own is only like Rank9, but I have talked with my FC on this subject and it was a general consensus that even with tank tree maxed out with some healing abilities, your chocobo is about as tanky as your average DPS player.

Which is kinda stupid, to be honest. What's the point in having a chocobo with "tanking" abilities that can't hold hate off of a DPS its level, even if you're not wearing endgame gear, and is worse at taking damage than a DPS player?

Yes, I get that they don't want a tank chocobo to be as good as a tank player (even though there is literally NOTHING in the open world where balance would be broken if chocobos Were that good other than maybe Hunts and the occasional FATE that nobody cares about), but yet if they are squishier and put out less enmity than a Melee DPS, then what's the point?

IMO, Tank Chocobos are 100% useless. You're better off going full DD first, then Heal second and just forget the tank tree. Or, take it just for the STR boosts. But do it last.