My advice is - go Acolyte if it's still available. Inquisitors-in-training fit that type of a character, and you can develop them without boundaries found in other places.
Not sure exactly what you mean by talker but you can definitely get Miria to talk for you if needed. Deran can vouch.
But I don't wanna be Inquisitor-in-Training.... Unless that is REALLY needed. Because you know, flexibility. She can't fake join cults. Her order and all that sort of crap would forbade her such action. Not to forget to properly lie. Battle-Sisters are all kind of raised in super excessive love of the emperor, justice and burning every heretic and mutant down. Not all too much.... Lying, like some hive scum has to on a day-to-day basis in order to survive. Seems we found something for me to do then. Plus could perhaps give some bonus points when dealing with Arbites of other worlds. Join in somewhere as an Enforcer and check out how deep corruption goes, etc. etc.
Well, if you allow Inquisitional Orkuisitor I'm using that chance. Although Kroot or Ogryn might be fun too.
I am implying she would be not all too convincing and can't go as far as necessary before feeling border-rim traitor. Especially while serving a Puritan
Do not assume to know how another character would feel. After all we're not talking about generic characters.
Of course we are not, but I go by a... Standard Battle Sister. They are upright and uptight alike. There is a reason why they are the ones chosen as the military arm of the Ordo Hereticus and nobody else. They are the only ones capable of being that righteous and I suppose ignorant to fight heretics without endangering themselves to become heretics, too. So do I. I had one in my Ordo Xenos RP and he was.... Fabulous ^^