I found a resource that helped me make up my mind on this:
Mr. Gaiman is a convert to the “no DRM” camp. His experience with piracy increasing demand for paid copies of his works is telling. Why indeed, since piracy seems to effectively be free advertising, should I use DRM? It would be counterproductive.
Besides, if I can unlock my entire library in one afternoon with less than an hour of web research, DRM is futile anyway.