Mike,
I would not sue. It would be an absurd waste of my energy, time, money, and life. The larger issue for me is not intellectual property or protecting my rights. I am just trying to keep someone from wasting my time and then handing the work I've just done for free for them to someone else to give them a headstart against me while I wonder what just happened.
Right off the bat, they can be cheaper because they get to quote something without having to 1) meet with the client and have a detailed conversation about the project, 2) turn that into a design concept, or 3) draw the concept in such a way as to be presentable to the client. They are several hundred dollars ahead of me right out of the gate -- all because of the free work I just did. That's what gets my goat.
That's why I like the idea of putting a "fence" up. If someone strolls into my yard, that's one thing, but if they jump my fence in order to do that, that's another. Fences do keep honest people honest, but they also keep the laziest dishonest people looking for an easier mark.
Securing the pdf may be more of a psychological barrier that reminds the average person that what is in that file is not for them to go sharing around with other companies. I'm sure someone with more chops than me could easily hack it, but that's not really the point. Actively dishonest people are not really what this thread is about. All you can do about them is try like crazy to avoid them.
