I can't comment about conversion, but what I can tell you is how AceDB-3.0 works.
- Create your Defaults table, local, in the main chunk
- Set up saved variables in OnInitialize() using profile, character, global, etc, either individually or combination
- Log into the game, change some settings, log out
You will then notice that the saved variables file only contains the changes you made to the settings, and not the entire batch of settings. This is very important to note, because it means AceDB has an extremely low footprint, keeping only the changes.
If you changed nothing, and left all the settings as default, then AceDB-3.0 would write nothing, and your saved variables file would be blank, or very close to blank.
By comparison, your saved variables file will contain everything, defaults and user altered settings, should you write using basic Blizzard code. That's great for addons with only a couple of settings, but for something like Carbonite, Pitbull4, all boss mods, or any addon of a complex nature, it becomes a beast.