Rush may be said to have evolved, but he did not "reinvent" himself.My view on him is he has reinvented himself several times. That's how you last a long time. Imus did too. So did Rush.
Imus in Cleveland early on was about the same, with rougher edges, that he was in NYC.
Stern has matured. He had childish almost early teen stuff back when he dressed like a penis. He wanted to do stuff that was shocking. Now he wants to say things that have meaning. So either I agree with you that Stern reinvented himself, or I make the distinction that he just matured; its about the same thing. Stern, of course, was about 40 or so when he finally became an adult.