Fortunately, the new COIN manual (FM 3-24) is very explicit in stating that torture and tolerating these types of "interrogation techniques" are unlawful and self-defeating:

1-132. Illegitimate actions are those involving the use of power without authority—whether committed by government officials, security forces, or counterinsurgents. Such actions include unjustified or excessive use of force, unlawful detention, torture, and punishment without trial. Efforts to build a legitimate government though illegitimate actions are self-defeating, even against insurgents who conceal themselves amid noncombatants and flout the law. Moreover, participation in COIN operations by U.S. forces must follow United States law, including domestic laws, treaties to which the United States is party, and certain HN laws. (See appendix D.) Any human rights abuses or legal violations committed by U.S. forces quickly become known throughout the local populace and eventually around the world. Illegitimate actions undermine both long- and short-term COIN efforts.
A great article that illustrates the ill effects of torture is in the Summer 2006 edition of Parameters by Lou DiMarco entitled Losing the Moral Compass: Torture and Guerre Revolutionnaire in the Algerian War:

http://www.carlisle.army.mil/usawc/p...er/dimarco.pdf

The official condoning of torture by French Army leaders had numerous negative effects that were not envisioned because of the army leadership’s intensive focus on tactical success. The negative results of torture included decreasing France’s ability to affect the conflict’s strategic center of gravity; internal fragmentation of the French Army officer corps; decreased moral authority of the army; setting the conditions for even greater violations of moral and legal authority; and providing a major information operations opportunity to the insurgency.