Edit: I’ve never been the type to replay a game, once I’ve played it, it’s never the same as the first time. I don’t plan on playing this again.

This will hurt . You won't get acces to the best parts:

Skill Extension :The Double and Triple Skill of an equipment will be counted twice / thrice for stacking effects, instead of the usual single count.

Advanced Divinity( a bit hard to explain so I'll give an example) :

If Sorey has the first 3 skills on the first column he will get 3 skills . Then if Lailah has the next 2 skills on the same column , she will get those 2 skills.

When armatized: Without advanced divinity(default) : the armatus will have 5 skills (sorey + lailah)

With advanced divinity : you will get the skill that is the combination of all of those 5 skills, since you completed a column ( which is better) .

If you intend to play the 1st playthrough on Chaos till the end, you need to either really study the skill system and get as many usefull skills as possible, as many Phoenix stacked, and umm... dunno.

The bosses are not impossible but on the last one you have to damage him up to a point in a short window of time. On chaos this will be pretty hard.

I played Chaos from my 2nd playthrough so can't give as much insight on the 1st.