Having played PvP more since I last commented on it, and played around with other jobs and observed others, I find this to be the most accurate take on where jobs are in terms of strength. Though I'd swap Gunbreaker and maybe Dancer with Paladin. Potentially swap Ninja with Warrior, or just bump Ninja down a tier.
I just don't find much redeeming about Dancer outside of being a dance partner and a situational AoE LB stun that has such a tight window to capitalize on; Whitemage's LB is almost superior in every way outside of differing AoE ranges. Because of it's nerfed attack range (why?), using DNC in Frontlines is almost a death sentence if they want to ever try to contribute with more than half of their skills (though job balance in Frontlines is a different beast for the most part, any job with a powerful AoE LB jumps to top tier). Maybe someone can explain to me why Dancer would be perceived to being a tier above Blackmage.
Paladin isn't strong, but feels like it executes its purpose as a classic tank/disrupter better than Gunbreaker (though Dark knight does it better). If Intervention actually had a stun though...
I think all healers are viable, with White mage and Astrologian having an edge. Sage doesn't have any reliable healing; it needs to be played somewhat aggressively and while being attentive to focused targets (or creating them) with Toxicon's debuff. Between that and their slightly larger (AoE) DPS kit, Sages can be solid provided targets are being focused down together with teammates. The shields and Kardia heals are mostly perks to staying on the offensive (though their LB is a godsend for pushing past the checkpoint/giving your team a breather... if they notice it). Scholar is interesting, in that you can regularly damage buff (and shield your entire team), or damage debuff (and DoT) grouped-up enemies, and increase the damage of the DoT or shield strength with an ability every half a minute that gives an AoE defense bonus. Their LB is also pretty good at keeping your team alive, and I'd argue this makes them the best at "healing," but only in that window of having Seraph. However, they have the worst direct-damage capacity (Mummification's range is pretty pitiful), so Scholars are basically left hoping the rest of their team can capitalize on their buffs.
While Whitemage has some solid abilities, it seems like it's carried entirely by their LB; I will be surprised if it survives a PvP balance patch unscathed. Being able to follow-up the LB with their instant AoEs usually means something is going to die with even a little bit of help from attentive teammates and the imp debuff being versatile enough as a defensive or offensive maneuver. I still stand by Astrologian being the most well-rounded healer, with a potential of up to 4 (instant) heals with HoTs or shields, AoE abilities that can inflict heavy and bind and Macrocosmos that's essentially a nuke to the enemy team and a (delayed) heal to your own. And if you have competent teammates, their balance and spire cards and limit break can quickly turn a fight in your favor.