It would take a *lot* of stacking of DA (DA-Khanda, DA trait, Brutal Earring, Aurore Doublet, Ferox Visor, etc.) to get to even a hard 30% DA proc rate, compared to the Trial 1204-OAT-Khanda's typical OAT proc rate I would guess?
Certainly swapping all that TP-generation/haste gear for DA gear at this point seems self-defeating. But maybe in the future if more DA trait is available it might be worthwhile, as DA will proc on both hands in dual-wield and might influence WS damage--which could arguably be better than OAT on a single hand, I would think.
We'll have to see what SE has in store. Sadly re-choosing a R/E sword type means redoing it all over again at this point, which I would imagine is SE's concept of "replay value" for FFXI. (They don't want Ruthven to get lonely out there.)