The people running the Agency at the time certainly believed the enhanced techniques worked, producing good information otherwise unobtainable. What's more, they continue to hold that opinion. And the minority (Republican) report agrees.
It is my opinion Feinstein started with a preconceived outcome in mind and selectively collected facts and testimony which supported that outcome. I believe she sought a finding which makes the U.S. look bad; something liberals love to do as it coincides with their view of our country as an international malefactor and bully.
That the CIA didn't use FBI techniques of information-gathering should surprise no one, their missions are almost entirely different. The FBI measures success in criminal convictions obtained, ideally one or more for each federal crime reported. The CIA brings no criminal cases, it collects information to support foreign policy decision-making and acts more or less covertly to stymie U.S. enemies, sometimes violently.
