With lower raid DPS, it was very possible to bloat your numbers to high hell in T13 with incessant AoE during the add phase, so hitting 500+ without Echo isn't implausible. The only fight in Final Coil where bloating really wasn't an option was T11 (which I still think is one of the best fight to truly judge a BLMs worth pre-echo). Also, I kinda see it hard for BLMs NOT to hit 500+ in T13, even with great DPS. Even the times when I come out of Add phase in horrible shape (480s after Tera), I can still leverage out at 525+.