According to the released torture memos, KSM gave up specific operatives before torture or waterboarding were applied. He gave up Majid Khan because he believed other operatives were "talking" (p 64-67 of this PDF), and not due to enhanced techniques. He gave information regarding Hambali and the planned bombing of Library Tower in LA, but nowhere in the memo does it say that enhanced techniques were required to obtain that information. KSM had been interrogated multiple times before enhanced techniques were used.
So while I may want to believe Hayden, I have no evidence to corroborate his opinion, and he was not director at the time. Meanwhile, the FBI interrogator, Ali Soufan, disagrees.
I'll conclude with John McCain:
“It’s unacceptable,” McCain said, adding:
"One is too much. Waterboarding is torture, period. I can ensure you that once enough physical pain is inflicted on someone, they will tell that interrogator whatever they think they want to hear. And most importantly, it serves as a great propaganda tool for those who recruit people to fight against us....McCain later reiterated his point, “The image of the United States of America throughout the world is a recruiting tool for Islamic extremists.”
The only outside assessment of the enhanced interrogation techniques (EIT) has come from ex-CIA Inspector General, John Helgerson, who recommended to the Obama administration that a bipartisan blue ribbon commission to look into the use of EIT to determine what is legal or useful. So far, this recommendation has been unheeded. To wit:
Although Helgerson said he accepted the conclusions of CIA managers that the brutal torture of detainees resulted in “valuable” intelligence, he believed the CIA has yet to provide definitive answers as to whether specific torture techniques were “effective” and “necessary” in obtaining intelligence or whether the same information could have been obtained through “traditional methods.”