Hades Sainti is pretty much useless for all jobs but NIN. I even said that to him when he were shouting catchy phrases in Aht Urhgan.
I still think Destroyers are better for MNK, even when tanking Salvage bosses. It increases your damage, thus killing him faster. Sure, the Enmity +9 gives you more total enmity, but on Long-Armed Chariot, your hate is reset during charm. On Long-Bowed Chariot, your hate is reset after Homing Missiles, unless you've weakened it. And in that case, he's easy anyway and should be tanked in Destroyers to speed up kill time.
Same applies to all bosses really. Its more beneficial for your WHMes and group as a whole if you kill it faster. If you hold hate fine against the others in the group, you generally don't need more enmity then you've got. Sure, it could possibly help the BLMes to nuke more, but are they really worth the price tag when Destroyers do the job just fine (which are free, btw)?
They're the best H2H weapons for PUP, but I'd say MNK's have better and cheaper choices.