  I have been giving some thought to the radical criticisms portion of the libertarian article since you first asked.  In part, I think many of these criticisms (at least from anarchists) are already present in wikipedia.  Some are in the anarcho-capitalism article, some are spread across a few other articles, and a few are actually represented in the AC criticisms of non-AC libertarianism.  So once I get around to it I might just throw in a link to another article or part thereof that has these criticisms to avoid redundancy.  Other than that I think the brief arguments outlined already are sufficient, though all of it could use a good round of citations and quotes, which is the pain I've been avoiding.  Anywho, I'll get around to it eventually unless someone beats me to it.     