IMO, clipping may increase the likelyhood of injury. For some birds , it doesnt affect their flying at all , and others it can inhibit the height they can reach.
Some drop like a stone as Roxy mentioned. I dont want to clip my guys unless I have to. I feel they can manuever much better with all feathers intact. With that said , you run the risk of them escaping through a window or open door. My Rosie was a terrible feather plucker when I got her , she is growing her feathers back nicely but it will be a while before she flys again. I was told by her previous owner that she flew very nicely and carefully around the house , so we will see how she does here. I have high ceilings and rafters she can land on and chew (awesome). I have seen my Goffin mis judge flying to me when I was sitting behind a glass door and end up aborting that landing and flying down the stairs instead , he made a perfect landing. If he didnt have his flight feathers I feel he would have had no choice other then to fly straight into the door and hurt himself. Unless they are very careless with their flying , I just think it's safer to leave their flight feathers intact. I also think they panic more if they have no control over their ability to avoid or choose their path.