I played both my BHers basically as galactic police officers. My Merc somehow ended up Light V (but that was after a lot of dailies) and my PT is Dark III or there about.
For the most part I made all my LS/DS choices based on what I would do if I was really in that exact scenario. There is almost always a non-lethal solution to every mark you encounter. When you do not have a choice and are forced to kill the mark, that is generally a hard coded event in the game. When the game forces your hand you shouldn't look at that as a reflection on the moral compass of your character.
I do fully agree that the stereotypical BH is far more likely to be a sociopath than the rest of the Imperial options. The profession simply lends itself to that mindset. Sith are indoctrinated with murder as a way of life simply by their "kill or die" academic experiences. But at some point in the life of every BH, they made an active decision to to take that as their chosen profession.
Just because Boba Fett is a sociopath doesn't mean every bounty hunter is. Go to Wookieepedia and look up "The Bounty Hunter's Creed' A bounty hunter that follows the Creed isn't at all a sociopath, in fact just the opposite. "Capture by Design, Kill by Necessity" is one of the rules. You're not an assassin if you follow the creed to the letter. I even played it that way... on one bounty this guy wanted me to kill someone, I didn't. I Captured her and I said "Here she is, she's helpless now if you want her dead, that's up to you."