Stat Wise it is true.
Codex system rewards about 4x iron skills (Decay wise) and more on low HP creatures (death roll bonus)
as per repeatables, just the ones that reward Attributs (if any still thre) are interesting,
again codex repeatables until repeat 8/9 beat the iron mission reward system.
but gears with a decent weapon and decent looter are a better source of income than sweating.
Onmuscle park there is (he is low level) a series of missions where Daikiba are shared with Caly.
Atrox on the shore are now too dense to be useful without high evader and a range weapon, they swarm in packs of 10 but the 65.000 kills iron is interesting. and the 10k kills repeatable counts toward caly codex too