I saw them once on the 2011 North American arena tour. I could have done without them, they kind of seemed like ways to fill time/give the band breaks. They were interesting on the album to make it flow together, but a live setting is different - it's less about flow, more about individual songs.
Some (The Requiem, Empty Spaces) made sense because the former opened the show and the latter was short. But others (The Radiance, Fallout) took up time that could have been used otherwise, and we basically just stood there during them. Even if they would have been taken out and replaced by nothing in the set, I think I would have preferred them talking to us during that time.
The crowd wasn't all that great for any of the show, but I don't think anyone really cared about the interludes from what I remember. Overall, they were not as useful live as they were on the album.