UN Peacekeeping... Hindrance?

The UN's biggest peacekeeping project right now is the Congo, but really, they're not that productive or helpful. At best, their successes are marginal. The mandate keeping 19,000 soldiers in the Congo expires in a few weeks according to Jeffrey Gettleman's article, but there is a lot of hesitation about whether or not it should be renewed. Much of the issue comes from the nature of the Congolese army, and their inclination to fight against the UN, and subsequently killl many civilians. So, that poses the question, is it better for the UN to stay out and save civilian lives, or be marginally successful (which is better than not successful at all) and have some lives taken??? It's all a matter of opinion I suppose because either way it seems as though the war isn't going anywhere.