I'm slightly confused. Your first post seemed to be implying that glider pilots manage OK despite flying in a less structured environment than powered pilots, because of their superior lookout skills. Your last post seemed to be admitting that actually glider pilots fly into things all the time, but are lucky because these accidents are less likely to be fatal.
My own feeling is that gliders and powered aircraft are so different and fly under such different conditions, that it's not really an useful conversation. From the overall safety perspective I'd be equally happy flying either - though given the choice I've enjoyed hang-gliding more than any other form of flying that I've done.