No Karma is gained or lost if the player character steals from containers belonging to criminal groups, such as the Powder Gangers, so long as their reputation with said group is "Vilified".
Fallout 3s Broken Steel dlc also adds "Albino Radscorpions" which are actually just stronger than any foe in the game and can take on multiple deathclaws and yao guais
I will say it feels a lot more dangerous to walk around than NV, where you just barely ever find anything dangerous. The most dangerous foes are legion hit squads, cazadors and deathclaws (sometimes)