Ahh....this old chestnut
Let's face it guys, if someone wants to rip you off they will, and you might never know about it.....the world is a big place, and the 'commercial sector' is full of ruthless bastards, who have no respect for what's legal or moral. Copyright, patents, design rights are not going to put off a determined counterfeiter/criminal from going about their everyday business. The idea that an established, respectable publisher, institution or artist might rip you off on the 'off chance' that you haven't protected your product is a non starter, as far as I'm concerned. They would probably have more to lose than they have to gain anyway. Personally, if I woke up one morning and heard one of my songs was a number one hit for Take That....I would be thrilled, not pssed off
I would THEN claim copyright, and ask them if they wanted any more
In fact, I would go as far as saying that being ripped off might be the best thing that could happen
I'm not saying that copyright isn't a good/positive thing, but I see it as mainly for my own 'peace of mind'
I think the 'bottom line' here is to seek your rewards from the enjoyment/satisfaction of creating and sharing your work....if financial success is your main aim, and 'raison d'etre', then, get a manager, and let him/her take care of all that stuff, while you concentrate on your art. Just don't worry too much about copyright
In my opinion, it's time, money, and energy that can be better spent elsewhere. Just my thoughts on the subject guys