So far as I can assess from the few times I've fought NMs with the turtle, I can say that Raphie is probably the closest thing to a pure tank that Beastmaster's ever been given. After fighting Wherwetrice for SCH head seals, the only times he was defeated was when I carelessly got petrified and couldn't use Reward. Harden Shell really does well in extending his durability and his resistance to enfeebling effects make cheap TP moves like Baleful Gaze much less of a threat. For the gil spent, Raphie certainly proves his value in battle.
On Falcorr, I'm rarely comfortable using THF jugs on NMs but Falcorr isn't too bad at closing things out if Raphie goes down towards the end. As a farming partner, he's does a lot better than Yuly in terms of kill speed and Fantod only adds to this. I can't say much about Jettatura since S-E doesn't seem to want players using it against anything that remotely resembles anything like an NM. Choke Breath is good but I cannot figure out the range of its effect. Overall, Falcorr is fast becoming a bargain given the rarity of the ingredients needed to make his jugs--then again, maybe that's because people have reason to fish up Abaias now.
That's a short summary of what I think of the value of these 2 pets.