Questions regarding Aigis DLC

Hey there, I am going through the three persona games, and I've beaten P4G and P5R, now the only one left in my list is Persona 3 Reload. I am very excited to play this game, however, I have a question regarding the Aigis expansion, and I would be glad if you could answer with no spoilers.

I can't help but compare this expansion to Royal (though idk how accurate this sentiment is) since I've heard it also adds more content after the end of the original game. Is it worth the steep price tag of 35 dollars? Also, if i decide to buy it later (maybe after i finish the original game), do I need to beat the game from scratch in order to access its content (making some specific choices during the main story etc.) , or is reloading from the last save enough?