Yes, there are some interesting side-effects when you attempt to motivate people to do very specific things. But, I don't think people leave the site or softwar

Yes, there are some interesting side-effects when you attempt to motivate people to do very specific things. But, I don't think people leave the site or software when certain badges are too hard. I think http://www.StackOverflow.com http://www.StackOverflow.com is a good example of where badges only add to the experience and don't get in the way.