A small factor as well is that once the patents expire, you have no advantage. As Coca Cola will attest, a secret can last for a lot longer. My feeling is tha

A small factor as well is that once the patents expire, you have no advantage. As Coca Cola will attest, a secret can last for a lot longer. My feeling is that you should use both. Patent the things you can't hide and keep secret the things you can. If you think the competition is close to duplicating what you've kept secret, patent it then if possible. Of course, if they, too, can keep it a secret, there's no point in patenting it. But if you know how to detect it, it might be worth patenting it.