As mentioned before, thanks to the High Defense of a character like Cepha, she's able to take about half the damage from regular 12-5 mobs as Paulia would, making her right on par with her for survivability. However, when fighting against bosses with their higher attack, the damage reduction isn't nearly as plentiful, only about 25% at most compared to Paulia, which is where the High-HP units shine (with maybe a 30% HP/Dmg buffer), especially in 12-5, where nearly every dam pest is actually a boss.