So looking at the wiki, infernalism supposedly boosts psi resistance per its description. But looking at the gamefiles 'armors_XCOMFILES.rul' I see:
psiDefence: &StandardDynamicPsiDefence
psiStrength: 1.0
psiSkill: 0.4
moraleCurrent: 0.33
bravery: 0.2
...
psiDefence: &InfernalDynamicPsiDefence
psiStrength: 1.0
psiSkill: 0.5
moraleCurrent: 0.33
bravery: 0.2
This implies that infernals get 0.1 of their psi skill as a bonus. But they also lose 30 bravery. Given 50 psi skill, isn't this a net negative? +5 from psi skill -6 from the bravery loss? Not to mention the max morale loss from having less bravery?
Most likely I'm missing something though, and I'd love to be enlightened. Would mean I don't have to differentiate between my soldiers based on psi strength as much in the midgame.