Whatever its utility, it seems clear now that torture, or indeed any form of aggressive interrogation, is indefensible in the public arena, and is therefore counterproductive. Indeed, while arguments can be made that US policies on coercive interrogation stopped short of some abstract definition of torture, whether or not this is true is less important than whether it can reasonably be argued to be untrue; because then while it may or may not produce useful intel, it will certainly produce a negative public reaction. In a conflict which will ultimately be decided by public opinion, it is a liaibility as a policy, as well as ethically untenable.

WRT your remark about what US abandonment of the Geneva Conventions will mean for captured US soldiers, I don't think it really matters. The paradigm has changed. Any country in the world that goes to war with the US will lose, and that briefly, if they fight according to the rules. Consequently the US will only be engaged in war with countries or forces that do not obey the rules, and therefore any captured US soldiers will be without any legal protection. This has been the case for a considerable time. The last war, arguably, that the US fought where its captured soldiers were usually treated in accordance with the Geneva Conventions, was WW2. Abu Graib, and the US policy on torture, is a serious liability for the US in this conflict and continues to be a motivation for their opponents, but even had it never taken place I think it is fantasy to imagine that anti-Coalition forces in Iraq would treat captured US troops properly, even if they had the facilities to do so.