HQ staff officer is an OW "Commander" advanced archtype.
A quartermaster is an Sage with the with the IG background
An investigative Arbiter would be a seeker with the Ad Arb. background. (which I think would be the standard rather than the warrior) Being Sherlock homes Vs. Judge Dredd is a matter of personality and subtlety.
I personally think of any DH character in much the same way as I think of 1st lvl D&D characters: They are rank beginners! With the elite advance system, I can even see them advancing into other "Standard" careers. For example: A warrior with the IG background could easily "elite advance" at 2000 xp. into an OW Weapon specialist or Heavy Gunner. (Or whatever if he had the right skill set!) . Further, I think it was intentional on ffg's part to allow for this kind of "Cross platform" Gaming.