I see no reason why taking items from the Powder Gangers is considered stealing. I mean, when killing them, you get good karma. When 'stealing' from them, you get bad. What the hell, guys?!

Shameless bump.

Don't worry about it.. high or low karma has no consequences in this game...only reputation matters.
And yeah it is kinda stupid that you can get karma for killing them..but lose it by stealing from them.