Throughout the history of rock and metal, there have been a number of groups who have replaced their lead singer for various reasons. It's no easy task. A band can replace a drummer with very little fanfare. They can replace a bassist and even a guitarist and generally continue on without fans blinking an eye. But replacing your front man, your lead singer, that's a tricky one. It has certainly been done before with varying degrees of success; Alice In Chains, Exodus and Anthrax did it. AC/DC and Van Halen have done it and continued or built upon previous successes. So has Iron Maiden.