but is Minthara a Shar type girl? Dunno
She's not necessarily pro-Shar, she's honestly quite similar to Astarion on that front. Both their life experiences fit pretty perfectly within the bounds of Shar's divine portfolio in terms of loss and living in darkness. And as Oath of Vengeance so long as whatever you're doing serves the party's goals she's in even if she doesn't end up approving of every little choice on the way.
My biggest thing against Hirelings is just that they have no reactivity. Minthara will at least chime in and add to the flavor of the playthrough.