The Myler philsophy centers around keeping horses comfortable and relaxed. "When the horse is resisting the current bit, it is too much bit for him and he can't relax." When izzy decides to be naughty, the ported barrel won't allow me any control which is why I am going to stick with the correction bit for a while. When he's behaving, we'll switch to the ported barrel. Hopefully he'll develop some confidence and decide that it's easier working with me rather than against me.
Check out the book. For the price, it's a super handy resource that offers easy to undestand explanations about a piece of tack that we riders don't always think about.