Hi, I just wanted to ask if there is any story/scenes/whatever added by the Mascots and 2.0 characters. Do I miss something by not taking them in NG+? Because I'm pretty happy with the characters I already have, I don't use all of them anyway and from what I understand I'll be still getting 4 other new characters in NG+.

Yes, there are some scenes with the angel maids after you join them and do their quests (no H-scenes though).
They also are fighters of varying but outstanding effectiveness.

2.0 characters - and I mean ones unlocked by the extra stories - don't have any events, but can be trained into veritable rapetrains.

You're not missing out on much story, but you will be missing out on great power.