Great discussion, there are some really great posts here.
Personally, I like wearing knee savers. I'm a freshman in college, and I haven't had a problem with them yet. In fact, the only time I ever use them is to give signals, but that is a welcomed break. The other 90 percent of the time I'm either in my receiving or runner on stances.
So, like many other posts, I don't think it is the knee savers that makes or breaks the catcher.