In my opinion DoA3 Hitomi is definitely different from Doa5, but some original traits of the character were brought back as her passion/seriousness for becoming a fighter, and her role appeared much more serious abandoning the absurd comic reliefs - as the cabbage or the dinosaur scenes - that made the girl airhead in DoA4 (element - together with the crazy circumstances - that instead is now attribuited to Kokoro, even if actually it's not genuine because part of her trolling). Hitomi in DoA5 has a kawaii side, but in general I think that she should be overall "classified" as a more positive and overactive version of her DoA3's one
I agree anyway that Mila is the character more close to the first Hitomi iteration.