Dialogue changed based on her H-development and many events change as a whole. There's even an indicator below dialogue windows when the part of conversation/event is affected by your H-stats and by what stat (for example, ass grabbing scene changes when your ass is more "developed").
Also, this time around you have to manually apply "level up" after reaching enough XP for that body part. So if you want her to behave like a total slut when somebody grabs her ass but threaten somebody with fireball when he grabbed her tits - you can do that.
They won't go back. As far I know, RPGmaker has become unable to handle their content and RPGMakerMV is a hassle and kinda outdated, too.
Thankfully, they did way better with unity this time than with Samurai Vandalism. I think there's no going back and we'll be seeing more and more use of Unity. Hopefully, as new games pop-up, so will tools to translate them.