No one will care about CT progression as it will be tied to the 16 other randoms in the group and will likely be too easy.

Extreme primals and ultima hard are the only progression worth caring about.

Playing from 1.0, extreme ifrit I would still say was the hardest fight, a massive step up from ifrit hard and it took a long time to beat but that could be more because if animation lock and lag, darnus hard was alot easier than ifrit Ex IMO.