Never had a problem with karma. In my opinion, the karma loss for killing innocents no matter what is good. It prevents stupidity. E.g. if someone sees an innocent kill another innocent in crossfire or accidentally you actually have a reason not to instantly kill them. I'm pretty sure that 75% of the time, people use the excuse "you killed an innocent so now i can kill you" just so that they can kill someone without getting in trouble, even if they have a strong feeling the other person is innocent.
Bottom line, don't play like a retard and it's unlikely you will ever go under 850 karma.
Bottom line, don't play like a retard and it's unlikely you will ever go under 850 karma.