With 4 batteries +2 torps it's not entirely usleless when it fails its reload order. I'd vote for that. True, pair of them could focus more firepower than Dictator, but they only have single shield [for both, assuming base contact to launch waves of 4, like Dictator can] and start losing effectivenes after 3 hits, comparing to Dictator's 4. Plus, Dictator has stronger torpedo salvo.
2 LFR lances would be over the top not in comparison with Dictator [both 2 Defiants and Dictator have their own poblems, roughly balancing each other] but with Endurance - Defiant would do its job nearly as good.
I like the idea of Defiant which apart from being supporting carrier can deal relatively solid punch to the front. Gives more reasons to use it.