I'll weigh in with my experience regarding DRM -- it's not worth it. The technology is unreliable and will work against you far more than it will ever do in your favour.
The only reason big companies (book publishers, video game publishers, etc.) get away with DRM is because their customer base has no choice but to accept it to get the product they want. The challenge for a small author, however, is to get people to want your product in the first place.
The simple fact is, people don't like jumping through hoops, especially when they're paying good money for the privilege. The desire to protect your work is understandable, but it's not realistic. Producing content on the internet is like being one voice in a choir of millions all fighting to be heard. If anyone actually wants to steal your work, they can and they will -- but if you make it difficult for honest readers to get to your content, they have so many other options available that they're not going to want the hassle of dealing with a crippled file. Some people refuse to use anything with DRM on it as a matter of principle.
The big thing at the heart of the DRM fallacy is that DRM doesn't deter pirates, but it does put off honest people who deserve to be able to use the file they bought without added headaches. It's worth remembering.