Hmmmm....
From what I've found, FBI agent Brad Garrett was successful in interrogating Yousef without extreme measures. Mostly he obtained simple confessions of what Yousef had already done, which may be one factor, but this is still an important piece of information in favor of conventional interrogation.
Garrett actually helped capture some of these guys in Pakistan.
Does anyone have more information on where conventional interrogation procedures have revealed plots still in progress? This isn't a challenge--I am really looking for information.